PubMed Health⌕ Search

Biomedical subjects

W M Mendenhall

Publications and source records attributed to W M Mendenhall.

At least 37 records · Page 2Linked to original sources
PubMed2000

Laryngeal or hypopharyngeal squamous cell carcinoma: can follow-up CT after definitive radiation therapy be used to detect local failure earlier than clinical examination alone?

PURPOSE: To determine if follow-up computed tomography (CT) after definitive radiation therapy for laryngeal or hypopharyngeal (laryngopharyngeal) carcinoma allows the detection of local failure earlier than clinical examination alone. MATERIALS AND METHODS: Pre- and post-radiation therapy follow-up CT scans in 66 patients were reviewed retrospectively. All patients underwent definitive hyperfractionated radiation therapy and were followed up clinically for at least 2 years after its completion. Post-radiation therapy CT scans (N = 153) were evaluated for posttreatment changes with a three-point score: A score of 1 represented expected posttreatment changes; 2, focal mass with a maximal diameter of less than 1 cm and/or asymmetric obliteration of laryngeal tissue planes; or 3, focal mass with a maximal diameter equal to or greater than 1 cm or estimated tumor volume reduction of less than 50%. All patients underwent the first posttreatment CT study 1-6 months after therapy. New or progressive laryngeal cartilage changes were noted. The clinical impression of the larynx at the time of each follow-up CT scan was also recorded. RESULTS: In 12 of 29 (41%) patients with treatment failure at the primary site, follow-up CT scans were definite for local failure (score, 3) a mean of 5.5 months (median, 3.5 months; range, 1-17 months) before clinical examination results. CONCLUSION: In many patients, follow-up CT shows local failure earlier than does clinical examination alone.

Adult↗
PubMed2000

Is radiation therapy a preferred alternative to surgery for squamous cell carcinoma of the base of tongue?

PURPOSE: To evaluate irradiation alone for treatment of base-of-tongue cancer. PATIENTS AND METHODS: Two hundred seventeen patients with squamous cell carcinoma of the base of tongue were treated with radiation alone and had follow-up for >/= 2 years. RESULTS: Local control rates at 5 years were as follows: T1, 96%; T2, 91%; T3, 81%; and T4, 38%. Multivariate analysis revealed that T stage (P =.0001) and overall treatment time (P =.0006) significantly influenced local control. The 5-year rates of local-regional control were as follows: I, 100%; II, 100%; III, 83%; IVA, 64%; and IVB, 65%. Multivariate analysis revealed that the following parameters significantly affect the probability of this end point: T stage (P =.0001), overall treatment time (P =.0001), overall stage (P =.0131), and addition of a neck dissection (P =.0021). The rates of absolute and cause-specific survival at 5 years were as follows: I, 50% and 100%; II, 81% and 100%; III, 65% and 76%; IVA, 42% and 56%; and IVB, 44% and 52%. Severe radiation complications developed in eight patients (4%). CONCLUSION: The likelihood of cure after external-beam irradiation was related to stage, overall treatment time, and addition of a planned neck dissection. The local-regional control rates and survival rates after radiation therapy were comparable to those after surgery, and the morbidity associated with irradiation was less.

Adult↗
PubMed2000

Radiation therapy for squamous cell carcinoma of the tonsillar region: a preferred alternative to surgery?

PURPOSE: There are no definitive randomized studies that compare radiotherapy (RT) with surgery for tonsillar cancer. The purpose of this study was to evaluate the results of RT alone and RT combined with a planned neck dissection for carcinoma of the tonsillar area and to compare these data with the results of treatment with primary surgery. PATIENTS AND METHODS: Four hundred patients were treated between October 1964 and December 1997 and observed for at least 2 years. One hundred forty-one patients underwent planned neck dissection, and 18 patients received induction (17 patients) or concomitant (one patient) chemotherapy. RESULTS: Five-year local control rates, by tumor stage, were as follows: T1, 83%; T2, 81%; T3, 74%; and T4, 60%. Multivariate analysis revealed that local control was significantly influenced by tumor stage (P =.0001), fractionation schedule (P =.0038), and external beam dose (P =.0227). Local control after RT for early-stage cancers was higher for tonsillar fossa/posterior pillar cancers than for those arising from the anterior tonsillar pillar. Five-year cause-specific survival rates, by disease stage, were as follows: I, 100%; II, 86%; III, 82%; IVa, 63%; and IVb, 22%. Multivariate analysis revealed that cause-specific survival was significantly influenced by overall stage (P =.0001), planned neck dissection (P =.0074), and histologic differentiation (P =.0307). The incidence of severe late complications after treatment was 5%. CONCLUSION: RT alone or combined with a planned neck dissection provides cure rates that are as good as those after surgery and is associated with a lower rate of severe complications.

Adult↗
PubMed1999

Pre- and post-radiotherapy computed tomography in laryngeal cancer: imaging-based prediction of local failure.

PURPOSE: To determine if pre-radiotherapy (RT) and/or post-radiotherapy computed tomography (CT) can predict local failure in patients with laryngeal carcinoma treated with definitive RT. METHODS AND MATERIALS: The pre- and post-RT CT examinations of 59 patients (T3 glottic carcinoma [n = 30] and T1-T4 supraglottic carcinoma [n = 29]) were reviewed. For each patient, the first post-RT CT study between 1 and 6 months after irradiation was used. All patients were treated with definitive hyperfractionated twice-daily continuous-course irradiation to a total dose of 6,720-7,920 cGy, and followed-up clinically for at least 2 years after completion of RT. Local control was defined as absence of primary tumor recurrence and a functioning larynx. On the pre-treatment CT study, each tumor was assigned a high-or low-risk profile for local failure after RT. The post-RT CT examinations were evaluated for post-treatment changes using a three-point post-RT CT-score: 1 = expected post-RT changes; 2 = focal mass with a maximal diameter of < 1 cm and/or asymmetric obliteration of laryngeal tissue planes; 3 = focal mass with a maximal diameter of > 1 cm, or < 50% estimated tumor volume reduction. RESULTS: The local control rates at 2 years post-RT based on pre-treatment CT evaluation were 88% for low pre-treatment risk profile patients (95% CI: 66-96%) and 34% (95% CI: 19-50%) for high pre-treatment risk profile patients (risk ratio 6.583; 95% CI: 2.265-9.129;p = 0.0001). Based on post-treatment CT, the local control rates at 2 years post-RT were 94% for score 1, 67% for score 2, and 10% for score 3 (risk ratio 4.760; 95% CI: 2.278-9.950 p = 0.0001). Post-RT CT scores added significant information to the pre-treatment risk profiles on prognosis. CONCLUSIONS: Pre-treatment CT risk profiles, as well as post-RT CT evaluation can identify patients, irradiated for laryngeal carcinomas, at high risk for developing local failure. When the post-RT CT score is available, it proves to be an even better prognosticator than the pre-treatment CT-risk profile.

Carcinoma, Squamous Cell↗
PubMed1999

A comparison of 3-D data correlation methods for fractionated stereotactic radiotherapy.

PURPOSE: Stereotactic radiosurgery is currently used to treat patients who are not good candidates for conventional neurosurgical procedures. For treatments of nonvascular tumor cells, it appears that fractionation offers a radiobiological advantage between tumor and normal tissues. Therefore, fractionated stereotactic radiotherapy (FSR) is preferred because it minimizes normal tissue complications and maximizes local tumor control probability. We have implemented a methodology clinically to perform the noninvasive patient repositioning technique. The 3-D data correlation method for high-precision and multiple fraction stereotactic treatments has been presented. METHODS AND MATERIALS: Three different optimization algorithms (Hooke and Jeeves optimization, simplex optimization, and simulated annealing optimization) are evaluated to calculate the transformation parameters necessary for FSR. A least-square object function is created to perform the 3-D data matching process. By minimizing the unconstrained object function value the best fit can be approached for the reference 3-D data sets. Simulation shows that these algorithms deliver results that are comparable to the previously published correlation algorithm (1,2) (singular value decomposition [SVD] method). The advantage for optimization algorithms is easily understood and can be readily implemented by using a personal computer (PC). The mathematical framework provides a tool to calculate the transformation matrix which can be used to adjust patient position for fractionated treatments. Therefore, using these algorithms for a high-precision fractionated treatment is possible without an invasive repeat fixation device and has been implemented clinically. A bite plate system was incorporated to acquire 3-D patient data. With a 3-D digital camera localization device, the patient motion can be followed in real time with the system calibrated to the isocenter. RESULTS: Two types of data sets are utilized to study the correlation results. One is using the digitized patient data which were retrieved clinically. The other is using the randomly generated data sets. Simulation errors for the optimization algorithms are all less than 1 mm in translation and less than 1 degree in rotation. Currently, FSR is performed using special designed repeat fixation devices which assure reproducible patient position for multiple fractions of radiation treatment. Clinical results indicated that this technique provided excellent treatment results. CONCLUSION: Three optimization algorithms have been applied and evaluated in calculating the transformation parameters between two 3-D contours or digitized data points. The mathematical functions behind these optimization algorithms are straightforward and can be easily implemented. When incorporated with the proper CT/MR image data with an electronic portal imaging (EPI) system, this process can possibly verify the patient's treatment position whenever there is doubt about the movement during the treatment procedure.

Algorithms↗
PubMed1999

Linear accelerator radiosurgery for nonacoustic schwannomas.

PURPOSE: To analyze the results of nonacoustic schwannomas treated with linear accelerator stereotactic radiosurgery. METHODS AND MATERIALS: Between August 1989 and October 1997, 18 patients with nonacoustic schwannomas underwent stereotactic radiosurgery at the University of Florida. Nine patients had schwannomas located in the jugular foramen region, seven in the trigeminal nerve, and two in the facial nerve. Nine patients had initial subtotal resections and nine did not undergo surgical intervention. One of the 9 patients with subtotal resection was treated with radiosurgery for a recurrent tumor. Tumor volumes ranged from 0.7 to 15.4 cm3 with a mean volume of 5.5 cm3. Minimal tumor doses ranged from 10.0 to 15.0 Gy with a mean dose of 13.1 Gy. Treatment dose was specified to the 80% isodose shell in 11 patients (58%) and to the 70% isodose shell in the remaining patients. Ten patients (56%) were treated with a single isocenter, 6 patients (33%) with 2-4 isocenters, and 2 patients (11%) with greater than 5 isocenters. Follow-up ranged from 5 to75 months and the mean follow-up was 32 months. Ten patients (56%) had follow-up beyond 2 years and none were lost to follow-up. Local control was defined as clinically stable neurological status and/or stable or decreased tumor size on yearly follow-up MR imaging. RESULTS: Eighteen evaluable patients (100%) had local control after treatment. All were alive and progression-free at last follow-up. Six of 10 patients with follow-up MRI 2 years or more after treatment had tumor regression and 4 patients had stable disease. Three additional patients with an MRI at 1 year showed no tumor change. Four complications in 3 patients included one worsening of a preexisting VII nerve palsy, 2 patients with new onset of hearing loss, and one with ataxia. No surgical intervention or prolonged steroid use was necessary for any patient with complications. Five patients had improvement in preexisting neurologic deficits. CONCLUSIONS: Excellent preliminary tumor control rates and a favorable toxicity profile support the effectiveness of linear accelerator stereotactic radiosurgery for patients with nonacoustic schwannomas.

Adolescent↗
PubMed1999

Skin cancer of the head and neck with incidental microscopic perineural invasion.

PURPOSE: To address outcomes in clinically asymptomatic patients in whom the unexpected finding of microscopic perineural invasion is noted at the time of surgery. METHODS AND MATERIALS: The 35 patients included in this study had skin cancers of the head and neck treated with curative intent between January 1965 and April 1995 at the University of Florida. All patients were without clinical or radiographic evidence of perineural invasion but, at the time of biopsy or surgical excision, had the incidental finding of microscopic perineural invasion. Definitive therapy consisted of radiotherapy alone after lesion biopsy (3 patients) or surgical excision preceded (2 patients) or followed (30 patients) by radiotherapy. All patients had follow-up for at least 1 year, 13 patients (37%) had follow-up for at least 5 years. RESULTS: The 5-year local control rate was 78%. The 5-year local control rate for the few patients treated with radiotherapy alone was statistically similar to that for patients treated with surgery and radiotherapy (100% vs. 77%, p = 0.4). Multivariate analysis for factors affecting local control included sex, histology, age, treatment group, clinical T stage, initial histologic differentiation, and previously untreated vs. recurrent tumors, none of which was found to be significant. CONCLUSIONS: Both surgery plus radiotherapy and radiotherapy alone provide a relatively high rate of local control for patients with incidentally discovered perineural invasion secondary to skin cancer.

Adult↗
PubMed1999

Linac radiosurgery for benign meningiomas.

PURPOSE: To review outcomes for patients treated with linac radiosurgery for benign meningiomas. METHODS AND MATERIALS: Between January 1989 and July 1997, 70 patients with 76 meningiomas were treated with LINAC-based radiosurgery. In 38 patients, radiosurgery was the initial treatment. In 32 patients, radiosurgery followed surgery or conventional radiotherapy. The average treatment volume was 10.0 cm3 (range, 0.6 to 28.6 cm3). The mean peripheral dose was 12.7 Gy (range, 10 to 20 Gy). The mean clinical follow-up period was 23 months. No patient was lost to follow-up. RESULTS: No lesions enlarged during the follow-up period; of 48 lesions in patients who had follow-up for at least one year and hence had follow-up imaging, 27 tumors remained unchanged and 21 tumors were reduced in size. Two patients experienced transient radiation-induced neurological deficits. One was treated with surgical excision of the tumor; the other responded to prolonged steroid therapy. Both patients, treated early in our experience, received doses higher than we would currently recommend. CONCLUSIONS: Early results suggest that stereotactic radiosurgery is an effective treatment for meningiomas. Long-term follow-up will be necessary to fully evaluate its efficacy.

Adult↗
PubMed1999

Squamous cell carcinoma of the nasal vestibule.

BACKGROUND AND METHODS: Sixty patients were treated with radiation therapy alone (56 patients) or followed by surgery (4 patients) between 1970 and 1995 for squamous cell carcinoma of the nasal vestibule. RESULTS: Local control rates at five years after irradiation alone in 56 patients were: T1-T2, 94%; T4, 71%; and overall, 85%. Multivariate analysis revealed that tumor size and bone invasion significantly influenced local control. All four patients with extensive T4 tumors treated with radiation therapy plus surgery were cured. Cause-specific survival rates at five years for 56 patients treated with radiation therapy alone were: T1-T2, 94%; T4, 86%; and overall, 91%. Multivariate analysis revealed that bone invasion and tumor size adversely influenced cause-specific survival. No patient treated with irradiation alone experienced a major complication, compared with three of four patients who underwent irradiation and surgery. CONCLUSIONS: Radiation therapy results in a high cure rate with good cosmesis. Patients with extensive T4 cancers have an improved chance of cure with radiation and surgery but more complications.

Adult↗
PubMed1999

Salvage treatment for neck recurrence after irradiation alone for head and neck squamous cell carcinoma with clinically positive neck nodes.

BACKGROUND: To analyze the likelihood of salvage for patients with recurrence in the neck after radiotherapy. METHOD: Recurrent disease developed in the neck of 51 patients after primary irradiation for head and neck carcinoma. Salvage was defined as no recurrence of cancer anywhere for at least 1 year after initial salvage treatment and continuously thereafter. RESULTS: Thirty-three patients (65%) did not undergo a salvage attempt: 18 had unresectable disease; 9 were medically unfit, 4 had distant metastasis; and 2 refused treatment. Eighteen patients (35%) underwent salvage treatment with chemotherapy alone (4 patients), chemotherapy and neck dissection (1 patient), neck dissection alone (11 patients), or surgery with radiotherapy (2 patients). After the initial salvage treatment, recurrent local-regional and/or distant disease developed in all patients. Recurrence was in the neck alone in 10 patients (55%); neck and distant sites in 3 patients (17%); neck, primary site, and distant sites in 2 patients (11%); and with distant metastasis alone in 3 patients (17%). Control of neck disease at 5 years was 9% for the 18 patients who underwent a salvage attempt, as well as for all 51 patients. For the overall group, absolute and cause-specific survival rates were both 10% at 5 years. CONCLUSIONS: The likelihood of successful salvage treatment after a neck recurrence following radiotherapy is remote.

Adult↗
PubMed1999

Induction chemotherapy and radiation therapy for T4 oropharyngeal carcinoma.

Between 1964 and 1996, 123 patients were treated for T4 oropharyngeal carcinoma; 93 were treated with radiation therapy alone; 30 were treated with induction chemotherapy and radiation therapy. Patients who received induction chemotherapy and radiation therapy were treated between 1985 and 1996; during this time 39 patients were treated with radiation therapy alone. Five-year local control rates for patients undergoing chemotherapy and radiation therapy, radiation therapy alone (all patients), and radiation therapy alone (patients treated since September 1985) were 63%, 38%, and 48%, respectively. The five-year rates of freedom from distant metastasis were 87%, 73%, and 76%, respectively. The five-year actuarial cause-specific survival rates were 58%, 27%, and 37%, respectively, while the five-year absolute survival rates were 42%, 17%, and 23%, respectively. Improvements in local control and freedom from distant metastasis in those receiving chemotherapy were not statistically significant, while the improvements in cause-specific survival and absolute survival were significant at the P < or = 0.05 level. Induction chemotherapy may improve the cure rate for patients with T4 oropharyngeal carcinoma. Although encouraging, these data are nonrandomized and should be interpreted with caution.

Adult↗
PubMed1999

The midline dose distribution for a three-field radiotherapy technique.

At the University of Florida, head and neck cancer often is irradiated using parallel opposed lateral fields (with inferior borders slanted superiorly) and an anterior low neck field. A common criticism is that overlap may occur at the match-line junction of the three fields, resulting in an increased risk of radiation myelitis. One setup for treatment of the oropharynx and two for the larynx were irradiated in an anthropomorphic head and neck phantom made of tissue-equivalent polyacrylamide gel with a two-dimensional thermoluminescent dosimeter array in its sagittal midplane. The results showed that no excess radiation dose was measured at the junction of the three fields. The "spinal cord dose," as percentage of dose to the central axis of the primary field, was as follows: oropharynx setup, 15% to 100%; larynx setup with midline tracheal block, 10% to 90%; larynx setup without tracheal block, 10% to 90%. In conclusion, the University of Florida three-field technique for head and neck cancer produces no measured increase in dose at field junctions.

Acrylic Resins↗
PubMed1999

Recent advances in the treatment and outcome of locally advanced rectal cancer.

OBJECTIVE: To compare the outcomes of treatment of locally advanced rectal cancer of the early era (1975-1990) with those of the late era (1991-1997). BACKGROUND: Preoperative therapy has been used in locally advanced rectal cancer to preserve sphincter function, decrease local recurrence, and improve survival. At the University of Florida, preoperative radiation has been used since 1975, and it was combined with chemotherapy beginning in 1991. METHODS: The records of 328 patients who underwent preoperative radiation or chemoradiation followed by complete resection for locally advanced rectal cancer defined as tethered, annular, or fixed tumors were reviewed. The clinicopathologic characteristics, adjuvant treatment administered, surgical procedures performed, and local recurrence-free and overall survival rates were analyzed. RESULTS: There were 219 patients in the early era and 109 in the late era. No significant differences were seen in patients (age, gender, race) or tumor characteristics (mean distance from the anal verge, annularity, fixation). Preoperative radiation regimens were radiobiologically comparable. No patient in the early era received preoperative chemotherapy, compared with 64 in the late era. Of those receiving any pre- or postoperative chemotherapy, three patients received chemotherapy in the early era, compared with 76 in the late era. Sphincter-preserving procedures increased from 13% in the early era to 52% in the late era. Pathologic downstaging for depth of invasion increased from 42% to 58%, but lymph node negativity remained similar. The 1-, 3-, and 5-year local recurrence-free survival rates were comparable. However, in the late era, 1-, 3-, and 5-year overall survival rates improved significantly compared with those of the early era, and also compared with each of the preceding 5-year intervals. CONCLUSION: The addition of a chemotherapy regimen to preoperative radiation therapy improves survival over radiation therapy alone. Likewise, an improvement in downstaging is associated with an increase in sphincter-preserving procedures.

Combined Modality Therapy↗