Biomedical subjects

S J Rubin

Publications and source records attributed to S J Rubin.

At least 19 recordsLinked to original sources

PubMed1999

Osteoarthritis and abnormal bone marrow of the mandibular condyle.

OBJECTIVE: The purpose of this study was to analyze the relationship between abnormal bone marrow of the mandibular condyle and osteoarthritis. STUDY DESIGN: The relationship between abnormal bone marrow and osteoarthritis of the mandibular condyle was analyzed in magnetic resonance images of the temporomandibular joints of 74 patients. Thirty-seven patients had magnetic resonance evidence of abnormal bone marrow, and 37 control patients had magnetic resonance images with normal bone marrow. RESULTS: Fifteen of 37 patients with magnetic resonance evidence of abnormal bone marrow had no magnetic resonance evidence of osteoarthritis; the other 22 patients had both abnormal bone marrow and osteoarthritis. CONCLUSIONS: Abnormal bone marrow of the mandibular condyle can occur separately from osteoarthritis; nearly one half of the joints with magnetic resonance evidence of abnormal bone marrow did not have any evident osteoarthritis. Abnormal bone marrow may therefore initially represent a separate disease entity. Over time, secondary osteoarthritis probably develops in joints with initial bone marrow abnormalities.

Adolescent↗

PubMed1998

Treatment of multifocal lymphoma of bone with intensified ProMACE-CytaBOM chemotherapy and involved field radiotherapy.

Primary bone involvement is an unusual extranodal presentation of non-Hodgkin lymphoma (NHL). The optimal treatment for this entity has not been determined. While solitary bone lymphomas can be eradicated with local radiation in 50% of patients, distant relapses occur frequently, and the treatment of patients with multifocal osseous disease, or those presenting with associated soft tissue invasion or adenopathy is even less satisfactory. Over a 4-year period, nine patients with multifocal bone lymphoma were treated with intensified versions of the ProMACE-CytaBOM regimen and involved-field radiation. Seven patients had diffuse large cell histology and two patients had diffuse mixed type. Seven patients survived event-free at a median follow-up of 2.3 years (range .5-3.5). In most survivors, there was little or no change in the abnormal radiographic bone findings despite the clinical response to therapy. In one patient, magnetic resonance imaging (MRI) established that bone infarction rather than relapse of lymphoma was the cause of a new lytic bone lesion that developed during treatment.

Adult↗

PubMed1998

Magnetic resonance imaging of the hip with a pelvic phased-array surface coil: a technical note.

OBJECTIVE: The aim of this study was to assess the capability of high-resolution images obtained with a commercially available pelvic phased-array surface coil to demonstrate normal hip anatomy. DESIGN: We retrospectively analyzed the oblique coronal magnetic resonance (MR) images of hips of 36 consecutive patients acquired on a 1.5-T clinical imager using a pelvic phased-array coil as a receiver, a 16-20 cm field of view, and 5 mm slice thickness. PATIENTS: Thirty-six patients were studied, age 15-81 years. There were 20 males and 16 females. RESULTS AND CONCLUSIONS: The articular cartilage, cortex, superior labrum, and iliofemoral ligament were well visualized on proton density weighted fat saturation (PDF) images. The femoral and obturator vessels, obturator nerve, and various muscles were easily seen on T1-weighted images. High-resolution imaging of the hip is achievable in a reasonable amount of time using newer phased-array surface coils and may play an increasing role in the future evaluation of hip disorders.

Adolescent↗

PubMed1998

Magnetic resonance imaging: a cost-effective alternative to bone scintigraphy in the evaluation of patients with suspected hip fractures.

OBJECTIVE: To evaluate the cost-effectiveness of magnetic resonance imaging (MRI) compared with radionuclide bone scan in the evaluation of patients with clinically suspected hip fractures. DESIGN: The medical records of all patients who had been seen in the emergency room over a 4 1/2 year period with a clinically suspected hip fracture, negative or equivocal plain films, and either a subsequent bone scan or MRI examination were retrospectively reviewed. The time to diagnosis, admission rate, and time to surgery were determined. A two-sample t-test was used to assess the statistical significance of the results. A theoretical cost analysis was performed using current charges to estimate all expenses. PATIENTS: Forty patients (11 male, 29 female; age 28-99 years) satisfied our inclusion criteria. RESULTS AND CONCLUSIONS: Twenty-one patients had bone scans (six with fractures), and 19 had MRI (four with fractures). The time to diagnosis was 2.24 +/- 1.30 days for bone scanning and 0.368 +/- 0.597 days for MRI (P < 0.0001). Twenty patients in the bone scan group were admitted compared with 13 in the MRI group. The time to surgery was at least 1 day longer in patients undergoing bone scanning. Bone scanning resulted in higher patient costs compared with MRI because of the delay in diagnosis. In the evaluation of patients with suspected hip fractures, early MRI is more cost-effective than delayed bone scanning. Further prospective studies comparing the cost-effectiveness of early MRI with early bone scanning are needed.

Adult↗

PubMed1998

MR imaging of rabbit hip cartilage with a clinical imager and specifically designed surface coils.

RATIONALE AND OBJECTIVES: The authors' purpose was to develop a magnetic resonance (MR) imaging technique for examining the hip joint of a rabbit with a clinical MR imager. MATERIALS AND METHODS: Fourteen hips of 10 male New Zealand white rabbits were examined on a 1.5-T MR imager with a specially designed surface coil. Field of view was 3-8 cm, matrix was 256-512 x 192-256, section thickness was 0.9-2.0 mm, and spacing was 0.3-0.5 mm. The hips were sectioned and evaluated by means of light microscopy. Measurements of cartilage thickness from MR images were correlated with those from histologic specimens. RESULTS: The resolution obtainable with a 1.5-T imager was adequate for imaging articular cartilage when a débrided rabbit hip specimen was placed in the center of a 3.5-cm single-loop coil. Rabbit hip cartilage had a trilaminar appearance on MR images. The coefficient of correlation between cartilage-thickness measurements was .81. CONCLUSION: MR imaging of rabbit hip cartilage can be performed on 1.5-T clinical MR imaging unit. Limitations due to the field strength can be overcome with efficiently designed surface coils.

Acetabulum↗

PubMed1998

Verification of the omni wedge technique.

The optimal field shape achieved using a multileaf collimator (MLC) often requires collimator rotation to minimize the adverse effects of the scalloped dose distribution the leaf steps produce. However, treatment machines are designed to deliver wedged fields parallel or perpendicular to the direction of the leaves. An analysis of cases from our clinic showed that for 25% of the wedged fields used to treat brain and lung tumors, the wedge direction and optimal MLC orientation differed by 20 degrees or more. The recently published omni wedge technique provides the capability of producing a wedged field with orientation independent of the orientation of the collimator. This paper presents a comparison of the three-dimensional (3D) dose distributions of the omni wedged field with distributions of wedged fields produced using both the universal and dynamic wedge techniques. All measurements were performed using film dosimetry techniques. The omni wedge generated fields closely matched the conventional wedged fields. Throughout 95% of the irradiated volume (excluding the penubra), the dose distribution of the omni wedged field ranged from +5.5 to -3.5 +/- 1.5% of that of the conventionally wedged fields. Calculation of the omni wedged field is as accurate as conventional wedged field calculation when using a 3D treatment planning systems. For two-dimensional treatment planning systems, where one must assume that the omni wedged field is identical to a conventional field, the calculated field and the delivered field differs by a small amount.

Brain Neoplasms↗

PubMed1997

Performance of a video-image-subtraction-based patient positioning system.

PURPOSE: We have developed and tested an interactive video system that utilizes image subtraction techniques to enable high precision patient repositioning using surface features. We report quantitative measurements of system performance characteristics. METHODS AND MATERIALS: Video images can provide a high precision, low cost measure of patient position. Image subtraction techniques enable one to incorporate detailed information contained in the image of a carefully verified reference position into real-time images. We have developed a system using video cameras providing orthogonal images of the treatment setup. The images are acquired, processed and viewed using an inexpensive frame grabber and a PC. The subtraction images provide the interactive guidance needed to quickly and accurately place a patient in the same position for each treatment session. We describe the design and implementation of our system, and its quantitative performance, using images both to measure changes in position, and to achieve accurate setup reproducibility. RESULTS: Under clinical conditions (60 cm field of view, 3.6 m object distance), the position of static, high contrast objects could be measured with a resolution of 0.04 mm (rms) in each of two dimensions. The two-dimensional position could be reproduced using the real-time image display with a resolution of 0.15 mm (rms). Two-dimensional measurement resolution of the head of a patient undergoing treatment for head and neck cancer was 0.1 mm (rms), using a lateral view, measuring the variation in position of the nose and the ear over the course of a single radiation treatment. Three-dimensional repositioning accuracy of the head of a healthy volunteer using orthogonal camera views was less than 0.7 mm (systematic error) with an rms variation of 1.2 mm. Setup adjustments based on the video images were typically performed within a few minutes. The higher precision achieved using the system to measure objects than to reposition them suggests that the variability in repositioning is dominated by the ability of the therapist to make small, controlled changes in the position of the patient. CONCLUSION: Using affordable, off-the-shelf technology, we have developed a patient positioning system that achieves repositioning accuracy normally associated with fractionated stereotactic systems. The technique provides real-time guidance and can be used to easily and quickly correct patient setup before every treatment, thus significantly reducing overall random positioning error. This improved positioning capability provides the precision required to realize the potential gains of conformal radiotherapy.

Computer Terminals↗

PubMed1997

Effective ultrasonographically guided intervention for diagnosis of musculoskeletal lesions.

Current algorithms recommend computed tomography or fluoroscopic guidance rather than ultrasonography for musculoskeletal intervention. We analyzed our ultrasonographically guided experience to evaluate its efficacy. Forty-seven patients underwent needle aspirates or biopsies or both in 13 extremity and 34 axial locations for 12 inflammatory lesions, 23 soft tissue masses, and 12 lesions arising from bone. Four lesions were initially imaged by ultrasonography; the remaining lesions were identified by computed tomography (25) or magnetic resonance imaging (18). Forty-six samples were diagnostic; one needle aspirate of an inflammatory mass yielded no diagnostic material. No complications occurred. Ultrasonographically guided musculoskeletal aspiration and biopsy are diagnostic and effective throughout the body, and with appropriate lesion access, they should be considered as an alternative to computed tomographic-guided procedures.

Adolescent↗

PubMed1996

The omni wedge: a method to produce wedged fields at arbitrary orientations.

A method to produce wedged fields at any orientation relative to the collimator is described. The wedged field is generated by combining two appropriately weighted orthogonal wedged field segments at fixed collimator and gantry positions. The method requires only that wedged fields can be produced in orthogonal directions without rotating the collimator, such as is commonly provided on most radiation therapy accelerators by sets of standard and rotated wedges. Expressions are derived relating the effective wedge angle and orientation to the weighting and wedge angles of the orthogonal wedged field segments. This technique will be important when using multileaf collimator field shaping for which collimator rotation is dictated by target or critical structure shape and orientation. The term omni wedge is introduced to describe this technique.

Biophysical Phenomena↗

PubMed1996

Repositioning accuracy of a noninvasive head fixation system for stereotactic radiotherapy.

We report on the repositioning accuracy of patient setup achieved with a noninvasive head fixation device for stereotactic radiotherapy. A custom head mask which attaches to our stereotactic radiosurgery head ring assembly is fabricated for each patient. The position and orientation of a patient in the stereotatic space at the time of treatment are determined from analyzing portal films containing images of radio-opaque spheres embedded in a custom mouthpiece. From analysis of 104 setups of 12 patients, we find that the average distance between the treated isocenter and its mean position is 1.8 mm, and that the standard deviations of the position of the treated isocenter in stereotactic coordinate space about its mean position are less than 1.4 mm in translation in any direction and less than 1 degree of rotation about any axis.

Equipment Design↗

PubMed1995

Comparison of static conformal field with multiple noncoplanar arc techniques for stereotactic radiosurgery or stereotactic radiotherapy.

PURPOSE: Compare the use of static conformal fields with the use of multiple noncoplanar arcs for stereotactic radiosurgery or stereotactic radiotherapy treatment of intracranial lesions. Evaluate the efficacy of these treatment techniques to deliver dose distributions comparable to those considered acceptable in current radiotherapy practice. METHODS AND MATERIALS: A previously treated radiosurgery case of a patient presenting with an irregularly shaped intracranial lesion was selected. Using a three-dimensional (3D) treatment-planning system, treatment plans using a single isocenter multiple noncoplanar arc technique and multiple noncoplanar conformal static fields were generated. Isodose distributions and dose volume histograms (DVHs) were computed for each treatment plan. We required that the 80% (of maximum dose) isodose surface enclose the target volume for all treatment plans. The prescription isodose was set equal to the minimum target isodose. The DVHs were analyzed to evaluate and compare the different treatment plans. RESULTS: The dose distribution in the target volume becomes more uniform as the number of conformal fields increases. The volume of normal tissue receiving low doses (> 10% of prescription isodose) increases as the number of static fields increases. The single isocenter multiple arc plan treats the greatest volume of normal tissue to low doses, approximately 1.6 times more volume than that treated by four static fields. The volume of normal tissue receiving high (> 90% of prescription isodose) and intermediate (> 50% of prescription isodose) doses decreases by 29 and 22%, respectively, as the number of static fields is increased from four to eight. Increasing the number of static fields to 12 only further reduces the high and intermediate dose volumes by 10 and 6%, respectively. The volume receiving the prescription dose is more than 3.5 times larger than the target volume for all treatment plans. CONCLUSIONS: Use of a multiple noncoplanar conformal static field treatment technique can significantly reduce the volume of normal tissue receiving high and intermediate doses compared with a single isocenter multiple arc treatment technique, while providing a more uniform dose in the target volume. Close conformation of the prescription isodose to the target volume is not possible using static uniform conformal fields for target shapes lacking an axis of rotational symmetry or plane of mirror symmetry.

Brain Neoplasms↗

PubMed1995

Photon neutron mixed-beam radiotherapy of locally advanced prostate cancer.

PURPOSE: In this article we present the results of mixed-beam, photon/neutron radiation therapy in 45 patients with locally advanced, bulky, or postoperative recurrent prostate cancer treated at the University of Chicago between 1978 and 1991. Survival, disease-free survival, local control, and long-term complications are analyzed in detail. METHODS AND MATERIALS: Between 1978 and 1991, 45 patients with locally advanced (> 5 cm State B2, Stage C, or Stage D1) prostate cancer underwent mixed-beam (photon/neutron) radiation therapy. Forty percent of the treatment was delivered with neutron irradiation at either the University of Chicago or Fermilab. Sixty percent of treatment was delivered with photons at the University of Chicago. Initially, the whole pelvis was irradiated to 50 photon Gy equivalent. This was followed by a boost to the prostate for an additional 20 photon Gy equivalent. RESULTS: The median follow-up for patients in this series is 72 months. The overall 5-year actuarial survival was 72%, and the 5-year disease-free survival was 45%. Thus far, 18 patients have died. Eleven patients have died from prostate cancer and 7 from other medical illness. Twenty-seven patients are alive, and 12 of these patients have recurrent and or metastatic disease. The local control rate was 89% (40 out of 45). Histologic material was available on 18 patients following treatment (i.e., prostate biopsy in 16 patients and autopsy in 2 patients) and was negative for carcinoma in 13 (72%). Significant Grade 3-5 complications occurred in 36% (16 out of 45) of the patients treated with mixed-beam radiation therapy and were related to dose and beam quality. Factors related to survival, disease-free survival, local control, and complications are analyzed. CONCLUSIONS: The survival and local control results of mixed-beam radiation therapy at the University of Chicago appear to be superior to those series using photon radiation in patients with locally advanced prostate carcinoma. Mixed-beam radiation therapy should remain an alternative to studies using dose escalation or implant techniques as a method to increase local control and survival at institutions with this capability. However, appropriate plans with high-energy neutrons are necessary to minimize complications.

Actuarial Analysis↗

PubMed1995

Conservative surgery and adjuvant radiation therapy in the management of adult soft tissue sarcoma of the extremities: clinical and radiobiological results.

PURPOSE: The outcome of adult patients with soft tissue sarcoma of the extremities treated with conservative surgery and adjuvant irradiation was evaluated to (a) determine the appropriate treatment volume and radiation dosage in the postoperative setting, and (b) correlate in vitro radiobiological parameters obtained prior to therapy with clinical outcome. METHODS AND MATERIALS: Sixty-four consecutive adult patients with soft tissue sarcoma of the extremities (40 lower, 24 upper) who underwent conservative surgery and adjuvant irradiation 7 preoperative, 50 postoperative, 7 perioperative) between 1978 and 1991 were reviewed. The initial radiation field margin surrounding the tumor bed/scar was retrospectively analyzed in all postoperative patients. Initial field margins were < 5 cm in 12 patients, 5-9.9 cm in 32 and > or = 10 cm in 6. Patients with negative pathological margins were initially treated with traditional postoperative doses (64-66 Gy); however, in later years the postoperative dose was reduced to 60 Gy. Thirteen cell lines were established prior to definite therapy, and radiobiological parameters (multitarget and linear-quadratic) were obtained and correlated with outcome. RESULTS: Postoperative patients treated with an initial field margin of < 5 cm had a 5-year local control of 30.4% vs. 93.2% in patients treated with an initial margin of > or = 5 cm (p = 0.0003). Five-year local control rates were similar in patients treated with initial field margins of 5-9.9 cm (91.6%) compared with those treated with > or = 10 cm margins (100%) (p = 0.49). While postoperative patients receiving < 60 Gy had a worse local control than those receiving > or = 60 Gy (p = 0.08), no difference was seen in local control between patients receiving less than traditional postoperative doses (60-63.9 Gy) (74.4% vs. those receiving 64-66 Gy (87.0%) (p = 0.5). The local control of patients treated in the later years of the study, with strict attention to surgical and radiotherapeutic technique, was 87.6%. Severe late sequelae were more frequent in patients treated with doses > or = 63 Gy compared to patients treated with lower doses (23.1% vs. 0%) (p < 0.05). Mean values for Do, alpha, beta, D, n and SF2 obtained from the 13 cell lines were 115.7, 0.66, 0.029, 2.15, 0.262, respectively. Four of the 13 cell lines established prior to therapy ultimately failed locally. The radiobiological parameters of these cell lines were similar to the other nine cell lines in terms of radiosensitivity. CONCLUSIONS: Our data confirm the importance of maintaining an initial field margin of at least 5 cm around the tumor bed/scar in the postoperative setting. No benefit was seen with the use of margins > or = 10 cm. In addition, patients undergoing wide local excision with negative margins can be treated with lower than traditional postoperative doses (60 Gy) without compromising local control and with fewer chronic sequelae. Finally, it does not appear that inherent tumor cell sensitivity is a major determinant of local failure following radiation therapy and conservative surgery in soft tissue sarcoma.

Adolescent↗

PubMed1994

Patterns of failure of complete responders following high-dose chemotherapy and autologous bone marrow transplantation for metastatic breast cancer: implications for the use of adjuvant radiation therapy.

PURPOSE: To determine the pattern of failure and outcome of patients achieving a complete response following high-dose chemotherapy and autologous bone marrow transplantation for metastatic breast cancer, and to evaluate the use of involved field radiation therapy in this setting. METHODS AND MATERIALS: Thirty-one patients with metastatic breast cancer treated on three successive high-dose chemotherapy and autologous bone marrow transplantation trials between January 1987 and March 1992 who achieved a complete response were evaluated. Twenty-three patients (74.2%) had initially Stage I-II disease. Initial therapy consisted of mastectomy in 19 (74.2%), adjuvant chemotherapy in 19 (61.3%), and adjuvant radiation therapy in 11 (35.5%). All patients underwent induction chemotherapy prior to high-dose intensification. High-dose chemotherapy consisted of cytoxan, thiotepa +/- carmustine. Fourteen patients received radiation therapy prior to (7) or following the high-dose chemotherapy (7) with either the intent to palliate a symptomatic disease site (4) or to attain/maintain a complete response (10). The four palliatively treated sites received 30 Gy in 3.0 Gy fractions, the sites treated definitively received a mean dose of 43.9 Gy (range, 18-64.8 Gy) in 1.5-2.0 Gy fractions. Seventy-two disease sites were present in the 31 patients. The most common sites involved were nodal (23), bone (14), and chest wall/breast (11). Nineteen sites were bulky (> 2 cm in size). Twenty-three sites were irradiated (19 definitively, 4 palliatively). Median follow-up was 18 months (range, 2-49 months). RESULTS: Twenty (64.5%) of the 31 patients relapsed. Eleven of the 17 patients not receiving radiation failed. Seven (63.6%) failed first solely in sites of previous disease involvement and four (36.4%) failed in new sites. This failure pattern was reversed in the patients receiving radiation therapy. Nine of the 14 (64.3%) patients relapsed. Two (22.2%) failed solely in old sites and six (66.7%) solely in new sites. One patient (11.1%) failed simultaneously in both old and new sites. Patients receiving radiation therapy had a similar 2-year actuarial disease-free survival compared to those not treated with radiation (28.3% vs. 32.1%) (p = 0.14). However, patients with less than three sites of disease had a better disease-free survival at 2 years with the addition of radiation therapy (30.0% vs. 17.6%) (p = 0.03). Patients with locoregional disease only had a lower rate of local failure (one out of four vs. three out of five) and a longer mean time to any failure (4.0 months vs. 17.5 months) with the addition of radiation therapy. Of the 72 sites identified, 59 (81.9%) were amenable to radiation therapy either prior to or following the transplant. The use of radiation therapy resulted in a borderline significant improvement in 2-year actuarial control of all sites (82.4% vs. 64.3%) (p = 0.09) as well as of bulky sites (80.0% vs. 51.4%) (p = 0.08). Excluding the four sites treated with palliative intent only, the 2-year actuarial local control of the irradiated sites was 92.8%. None of the 14 treated patients experienced untoward sequelae. CONCLUSION: The predominant site of initial failure in patients with metastatic breast cancer achieving a complete response following high-dose chemotherapy and autologous bone marrow transplantation is in sites of previous disease involvement. Radiation therapy given in conjunction with the high-dose chemotherapy is capable of improving the control of these sites, the majority of which are amenable to treatment with radiation therapy. Our data suggests that patients with less than three sites of disease, bulky disease, and locoregional disease only should be considered for radiation therapy in addition to high-dose chemotherapy.

Adult↗

PubMed1994

O'Donoghue's triad: magnetic resonance imaging evidence.

OBJECTIVE: The objective was to search for magnetic resonance imaging evidence of medial collateral ligament (MCL) injury in knees with proven tears of the anterior cruciate ligament (ACL) and medial meniscus; the three abnormalities that make up O'Donoghue's triad. Although the MCL injury can be unapparent clinically, knee joint stability may be compromised. DESIGN: The superficial portion of the MCL was evaluated on 19 MR studies of 16 knees with arthroscopically proven ACL and medial meniscal tears. MCL thicknesses were compared to those on MR images of 19 normal knees. PATIENTS: The injured knees were of 13 men and 3 women, ranging in age from 19 to 56 years; the normal knees were of 10 men and 9 women, ranging in age from 19 to 55 years. RESULTS AND CONCLUSIONS: The medial collateral ligaments of all injured knees were abnormal, and, as a group, they had greater thicknesses and more intraligamentous thickness variability than normal knees. The MR appearance of both ACL and medial meniscal tears served as indirect evidence of MCL injury, with irregular MCL thickening indicative of prior injury.

Adult↗

PubMed1992

Heterogeneous in vivo MR images of soft tissue tumors: guide to gross specimen sampling.

Twelve soft tissue tumors preoperatively studied with magnetic resonance (MR) imaging contained areas of inhomogeneous intralesional signal intensity. The pathologist's selection of biopsy sites from gross specimens was based on specific MR images selected by a radiologist and depended on close cooperation between the radiologist and pathologist. The histopathology so sampled, further depended on the lesion's size, careful gross specimen orientation, discrete sampling, and a specially developed Grid Analysis technique. Our initial experience indicates that (1) histology may vary within different and often neighboring sites of a single soft tissue lesion; (2) that such variability is common in soft tissue tumors; (3) that histological variability within different sites of a single lesion influences signal heterogeneity; and (4) that although differing MR signal intensities per se are not tissue specific, MR may enhance the histopathological accuracy of pathologists who can be directed to particular gross specimen sites by magnetic resonance images. To our knowledge such a specific, detailed effort has not been made.

Adult↗

PubMed1992

Localized prostate cancer: use of serial prostate-specific antigen measurements during radiation therapy.

The serum half-life of prostate-specific antigen (PSA) after radical prostatectomy is about 3 days; to the authors' knowledge, the PSA half-life during radiation therapy (RT) has not been investigated with weekly serial measurements. To determine the rate of decline and the half-life of PSA, serial measurements were obtained during 6-8 weeks of external-beam RT for localized prostate cancer. PSA values were determined immediately before and approximately 24 hours after the first dose of RT; thereafter, weekly measurements were made. There was a downward trend in PSA levels in 19 patients, with a median half-life of 58.5 days; the mean decline was 1.6% per day. However, in four patients, PSA levels either rose and fell to pre-RT values or increased steadily. The effect of digital rectal examination (DRE) on PSA levels was also analyzed. When the dates of DRE and subsequent PSA levels were inspected, no increase in PSA levels subsequent to DRE was found, although three of the four patients in whom PSA levels did not decrease underwent multiple DREs. The authors found a statistically significant (P = .023) transient elevation in the mean PSA values after the first fraction of RT (2 Gy) was administered; the mechanism and importance of which are not known.

Adenocarcinoma↗

PubMed1991

Two prostate carcinoma cell lines demonstrate abnormalities in tumor suppressor genes.

Two prostate carcinoma cell lines, DU-145 and PC-3, were examined for abnormalities in the retinoblastoma (Rb) and the p53 putative tumor suppressor genes. We found an abnormal Rb gene product in DU-145 using Western blot analysis. Polymerase chain reaction amplification followed by direct DNA sequencing demonstrated a base substitution mutation that generates a stop codon in exon 21. On Northern, Southern, and Western blot analysis, the p53 gene and its product appear to be normal in DU-145. PC-3, however, failed to demonstrate expression of either the p53 transcript on Northern blot analysis or the p53 protein on Western blot analysis, while the Rb gene products appeared to be normal on both Northern and Western blot analysis. This work extends the correlation between abnormal expression of putative tumor suppressor genes and human malignancies.

Base Sequence↗