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Biomedical subjects

C T Chung

Publications and source records attributed to C T Chung.

At least 19 recordsLinked to original sources
PubMed2001

Enhanced apoptosis and radiosensitization by combined 13-cis-retinoic acid and interferon-alpha2a; role of RAR-beta gene.

PURPOSE: Combined use of 13-cis-retinoic acid (cRA) and interferon-alpha2a (IFNalpha) induced significant radiosensitization in human cervical cancer ME-180 cell line, whereas it failed to achieve similar radiation enhancement in HeLa cells. The differential radiosensitization could be from the difference of retinoic acid receptor (RAR) expression because RAR-beta was highly expressed in ME-180 cells in contrast to the HeLa cells where RAR-beta was not detectable. We examined the role of this gene in mediating radiosensitization by cRA and IFNalpha, and explored the mechanism of radiation-induced cell killing. METHODS AND MATERIALS: Human cervical cancer cell lines, ME-180 and HeLa, were treated with cRA and IFNalpha followed by radiation. Apoptosis and radiosensitization were quantitated by TUNEL assay (in situ DNA nick end labeling) and colony-forming ability of surviving cells. The cells were transfected with bcl-2 gene and RAR-beta gene to test the role of these genes in mediating radiosensitization and apoptosis. RESULTS: Synergistic radiosensitization and apoptosis was observed by combined use of cRA and IFNalpha with radiation in ME-180 cells which express high level of RAR-beta mRNA, whereas these were not seen in HeLa cells where RAR-beta mRNA is not detectable. Both radiosensitization and apoptosis were abolished by bcl-2 gene in ME-180 cells. RAR-beta gene transfection induced similar radiation enhancement and apoptosis in HeLa cells. CONCLUSION: Apoptosis and radiation response were enhanced in the cells with high level of RAR-beta mRNA expression. The RAR-beta gene appears to mediate the radiation-induced apoptosis by cRA and IFNalpha. These findings indicate that presence of RAR-beta in the cancer cells could be exploited for patient selection in using these drugs for apoptosis and radiosensitization.

Antineoplastic Agents↗
PubMed2000

'Full dose' reirradiation of human cervical spinal cord.

With the progress of modern multimodality cancer treatment, retreatment of late recurrences or second tumors became more commonly encountered in management of patients with cancer. Spinal cord retreatment with radiation is a common problem in this regard. Because radiation myelopathy may result in functional deficits, many oncologists are concerned about radiation-induced myelopathy when retreating tumors located within or immediately adjacent to the previous radiation portal. The treatment decision is complicated because it requires a pertinent assessment of prognostic factors with and without reirradiation, radiobiologic estimation of recovery of occult spinal cord damage from the previous treatment, as well as interactions because of multimodality treatment. Recent studies regarding reirradiation of spinal cord in animals using limb paralysis as an endpoint have shown substantial and almost complete recovery of spinal cord injury after a sufficient time after the initial radiotherapy. We report a case of "full" dose reirradiation of the entire cervical spinal cord in a patient who has not developed clinically detectable radiation-induced myelopathy on long-term follow-up of 17 years after the first radiotherapy and 5 years after the second radiotherapy.

Adult↗
PubMed2000

Aggressive radiotherapy adjuvant to peripheral blood stem cell transplant for relapsed Hodgkin's disease.

The role of radiotherapy in conjunction with high-dose chemotherapy and autologous bone marrow transplant for relapsed Hodgkin's disease remains to be clearly defined. Although there is substantial evidence that radiotherapy enhances local tumor control, prospective trials in the transplant setting have not been reported, and the potential toxicity of radiotherapy need to be considered. However, certain patients are at high risk of posttransplant tumor recurrence, most notably those with tumors unresponsive to pretransplant chemotherapy. We report the use of aggressive radiotherapy in three high-risk patients, including the first reported case of whole lung irradiation after a high-dose carmustine-based chemotherapy regimen. Two of these patients received repeat partial lung irradiation, including one patient with carmustine-related pulmonary toxicity. Radiotherapy (30-34.5 Gy; 1.5 Gy/fraction) was tolerated well without significant acute or late toxicity, and all patients remain disease free 40 to 62 months after irradiation without severe sequelae. We conclude that radiotherapy may be of benefit for patients at high risk of local tumor relapse, and should be considered in such cases despite potential toxicity.

Adult↗
PubMed2000

Hematologic toxic reaction to radiation therapy adjuvant to autologous peripheral blood stem cell transplantation for recurrent or refractory Hodgkin disease.

PURPOSE: To evaluate the hematologic toxic reaction to external-beam radiation therapy after high-dose chemotherapy with peripheral blood stem cell (PBSC) support in patients with Hodgkin disease. MATERIALS AND METHODS: A retrospective study of 30 cases of Hodgkin disease in patients who underwent high-dose carmustine, etoposide, and cyclophosphamide chemotherapy with PBSC support was performed. Thirteen patients underwent radiation therapy (28.8-39.0 Gy) a median of 45 days after PBSC repeat infusion. RESULTS: Radiation therapy was delivered as planned, without interruption, in all patients. Five patients developed thrombocytopenia (one with grade 1 thrombocytopenia; two, grade 2; and two, grade 3) and included three with progressive disease prior to radiation therapy and two with a history of prior irradiation. None developed a bleeding complication or required transfusion support. Five patients who underwent irradiation had thrombocytopenia (three with grade 1 and two with grade 2) 100 days after PBSC repeat infusion, compared with three patients (two with grade 1 and one with grade 3) who did not undergo posttransplantation irradiation. At the most recent follow-up, no patient without evidence of disease had a platelet count of less than 100 x 10(9)/L. CONCLUSION: External-beam radiation therapy was well tolerated in the posttransplantation setting in patients with Hodgkin disease. Thrombocytopenia was common but was not related to clinical complications.

Adolescent↗
PubMed2000

Neurogenic intermittent claudication related to spinal stenosis.

BACKGROUND: The pathophysiology of neurogenic intermittent claudication (NIC) is not very well understood. We examined the theory of "two-level" spinal stenosis as the pathologic cause of NIC. METHODS: Forty-five consecutive patients with NIC were chosen for the study group and another 45 patients with chronic low back pain, but without NIC, were consecutively chosen for the control group. All the patients were examined using several methods that included a personal history survey, physical examination, X-ray studies, computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: Two-level central canal stenosis was found on MRI in 88.9% of the study group compared to only 37.8% of the control group (Fisher's exact two-tailed test, P = 0.0000). In the study group, 77.8% of the patients had severe or moderate facet joint degeneration on CT. The remaining 22.2% of patients had mild facet joint degeneration. In the control group, 40% of the patients had severe or moderate facet joint degeneration, while it was mild or normal in the remaining 60% (Fisher's exact two-tailed test, P = 0.0005). On X-ray, 42.2% of the study group compared with 17.7% of the control group had spondylolisthesis (Fisher's exact two-tailed test, P = 0.0129). In 35% of the study group compared with 11.1% of the control group, X-ray findings showed scoliosis (Fisher's exact two-tailed test, P = 0.0115). The lumbosacral angle in the study group was 35.8 degrees +/- 6.1 degrees compared to 33.1 degrees +/- 7.5 degrees in the control group (independent Student's two-tailed t-test, P > 0.05). CONCLUSIONS: Our study strongly supports pathophysiology for NIC that is closely related to two-level spinal canal stenosis. Degenerative joint disease, spondylolisthesis and scoliosis of the lumbar spine are predisposing factors of NIC.

Humans↗
PubMed1999

Sequential chemotherapy (etoposide, vinblastine, and doxorubicin) and subtotal lymph node radiation for patients with localized Hodgkin disease and unfavorable prognostic features: A phase II Cancer and Leukemia Group B Study (9051).

BACKGROUND: The aim of this study was to evaluate a regimen of sequential chemotherapy and radiotherapy for patients with Hodgkin disease. METHODS: The Cancer and Leukemia Group B conducted a Phase II study of three cycles of etoposide, vinblastine, and doxorubicin (EVA) chemotherapy followed by subtotal lymph node radiation for patients with localized Hodgkin disease and unfavorable prognostic features. Fifty-nine patients were enrolled in the study. Fifty-three patients met all study eligibility criteria; 48 of them (91%) had mediastinal disease and 29 (55%) had bulky mediastinal disease. RESULTS: A complete response (CR) occurred in 35 of the patients (66%). Of all patients who had CR, 26% had the CR after the chemotherapy and before the radiation, and 74% after the chemotherapy and radiation. Twenty percent of the patients who had CR experienced disease progression; in these patients, the progression was outside the radiotherapy field in the lung and involved widespread disease. CONCLUSIONS: EVA offers a nonbleomycin-containing alternative for patients in whom preexisting pulmonary disease may be exacerbated by bleomycin and radiation therapy. EVA, as given in this study (in three cycles), was insufficient chemotherapy for patients who had disease in areas outside the radiation fields (occult disease).

Adolescent↗
PubMed1998

The value of gallium imaging after therapy for Hodgkin's disease.

BACKGROUND: Although it is used widely, the value of gallium imaging in managing Hodgkin's disease remains unclear. METHODS: A retrospective review of gallium imaging and treatment outcome in 60 patients with Hodgkin's disease treated between January 1990 and July 1995 was conducted. The minimum follow-up was 1 year. RESULTS: Based on gallium imaging, 46 patients were in complete remission (CR) after initial treatment, 10 were in partial remission (PR), and 4 had persistent or progressive disease (NR). Ten of 29 patients (34%) with gallium CR after chemotherapy subsequently recurred, compared with no recurrences in 17 patients receiving initial radiotherapy or combined chemoradiation. Eight of ten patients received further therapy after gallium PR, and nine patients remained disease free at last follow-up. Survival did not differ in patients achieving a gallium CR or PR. CONCLUSIONS: Gallium-67 imaging may help confirm the presence of active Hodgkin's disease, but was unreliable in defining disease remission after chemotherapy in this study population. Patients with a gallium PR may still have a good prognosis after additional therapy.

Adolescent↗
PubMed1998

Phase I study to determine the maximum-tolerated dose of radiation in standard daily and hyperfractionated-accelerated twice-daily radiation schedules with concurrent chemotherapy for limited-stage small-cell lung cancer.

PURPOSE: An improvement in radiation dose schedule is necessary to increase local tumor control and survival in limited-stage small-cell lung cancer. The goal of this study was to determine the maximum-tolerated dose (MTD) of radiation (RT) in both standard daily and hyperfractionated-accelerated (HA) twice-daily RT schedules in concurrent chemoradiation. METHODS: The study design consisted of a sequential dose escalation in both daily and HA twice-daily RT regimens. RT dose to the initial volume was kept at 40 to 40.5 Gy, while it was gradually increased to the boost volume by adding a 7% to 11 % increment of total dose to subsequent cohorts. The MTD was defined as the radiation dose level at one cohort below that which resulted in more than 33% of patients experiencing grade > or = 4 acute esophagitis and/or grade > or = 3 pulmonary toxicity. The study plan included nine cohorts, five on HA twice-daily and four on daily regimens for the dose escalation. Chemotherapy consisted of three cycles of cisplatin 33 mg/m2/d on days 1 to 3 over 30 minutes, cyclophosphamide 500 mg/m2 on day 1 intravenously (IV) over 1 hour, and etoposide 80 mg/m2/d on days 1 to 3 over 1 hour every 3 weeks (PCE) and two cycles of PE. RT was started at the initiation of the fourth cycle of chemotherapy. RESULTS: Fifty patients were enrolled onto the study. The median age was 60 years (range, 38-79), sex ratio 2.3:1 for male to female, weight loss less than 5% in 73%, and performance score 0 to 1 in 94% and 2 in 6% of patients. In HA twice-daily RT, grade > or = 4 acute esophagitis was noted in two of five (40%), two of seven (29%), four of six (67%), and five of six patients (86%) at 50 (1.25 Gy twice daily), 45, 50, and 55.5 Gy in 1.5 Gy twice daily, 5 d/wk, respectively. Grade > or = 3 pulmonary toxicity was not seen in any of these 24 patients. Therefore, the MTD for HA twice-daily RT was judged to be 45 Gy in 30 fractions over 3 weeks. In daily RT, grade > or = 4 acute esophagitis was noted in zero of four, zero of four, one of five (20%), and two of six patients (33%) at 56, 60, 66, and 70 Gy on a schedule of 2 Gy per fraction per day, five fractions per week. Grade > or = 3 pneumonitis was not observed in any of the 19 patients. Thus, the MTD for daily RT was judged to be at least 70 Gy in 35 fractions over 7 weeks. Grade 4 granulocytopenia and thrombocytopenia were observed in 53% and 6% of patients, respectively, during the first three cycles of PCE. During chemotherapy cycles 4 to 5, grade 4 granulocytopenia and thrombocytopenia were noted in 43% and 29% of patients at 45 Gy in 30 fractions over 3 weeks (MTD) by HA twice-daily RT and 50% and 17% at 70 Gy in 35 fractions over 7 weeks (MTD) by daily RT, respectively. The overall tumor response consisted of complete remission (CR) in 51% (24 of 47), partial remission (PR) in 38% (1 8 of 47), and stable disease in 2% (one of 47). The median survival time of all patients was 24.4 months and 2- and 3-year survival rates were 53% and 28%, respectively. With regard to the different radiation schedules, 2- and 3-year survival rates were 52% and 25% for the HA twice-daily and 54% and 35% for the daily RT cohorts. CONCLUSION: The MTD of HA twice-daily RT was determined to be 45 Gy in 30 fractions over 3 weeks, while it was judged to be at least 70 Gy in 35 fractions over 7 weeks for daily RT. A phase III randomized trial to compare standard daily RT with HA twice-daily RT at their MTD for local tumor control and survival would be a sensible research in searching for a more effective RT dose-schedule than those that are being used currently.

Adult↗
PubMed1997

Increased risk of breast cancer in splenectomized patients undergoing radiation therapy for Hodgkin's disease.

PURPOSE: Second malignancies have been reported among patients who were treated by radiation therapy or chemotherapy alone or in combination. Studies have implied an increased risk of breast cancer in women who received radiotherapy as part of their treatment for Hodgkin's disease. This review was performed to determine if there is an association between splenectomy and subsequent breast cancer. METHODS AND MATERIALS: One hundred and thirty-six female patients with histologically proven Hodgkin's disease were seen in the Division of Radiation Oncology between 1962 and 1985. All patients received mantle or mediastinal irradiation as part of their therapy. The risk of breast cancer was assessed and multiple linear regression analysis was performed on the following variables: patient age, stage, dose and extent of radiation field, time after completing radiation therapy, splenectomy, and chemotherapy. RESULTS: Breast cancer was observed in 11 of 74 splenectomized patients and in none of 62 patients not splenectomized. The mean follow-up was 13 years in splenectomized patients and 16 years, 7 months in nonsplenectomized patients. Nine patients developed invasive breast cancer and two developed ductal carcinoma in situ. Splenectomy was the only variable independently associated with an increased risk of breast cancer (p < 0.005) in multiple linear regression analysis; age, latency, and splenectomy considered together were also associated with an increased risk of breast cancer (p < 0.01). CONCLUSION: Our data show an increased risk of breast cancer in splenectomized patients who had treatment for Hodgkin's disease. A multiinstitutional survey may better define the influence of splenectomy relative to developing breast cancer in patients treated for Hodgkin's disease. The risk of breast cancer should be considered when recommending staging laparotomy, and we recommend close follow-up examination including routine mammograms for female patients successfully treated for Hodgkin's disease.

Adolescent↗
PubMed1995

Surface dose for tangentially incident photon beams in the presence of air gap and air cavity.

Dose to a surface parallel to an incident photon beam has been investigated in the presence of air gaps and air cavities. Measurements have been made in an acrylic phantom with a parallel plate chamber. Photon beams of Co 60, 4-MV, 6-MV, and 15-MV X-rays have been investigated. The results of our measurements show that in the case of air gaps, the dose reduction to a tangential surface is considerable. On the other hand, the dose reduction is 2% or less in the case of air cavity for volumes encountered in clinical situations.

Air↗
PubMed1994

Radiotherapy for nasolacrimal tract epithelial cancer.

PURPOSE: Tumors of the lacrimal sac are rare and have traditionally been treated surgically. We investigated the use of irradiation for treatment. METHODS AND MATERIALS: Three consecutive patients with primary epithelial cancer of the nasolacrimal apparatus were treated with irradiation. A tumor dose of 52-66 Gy was delivered with conventional fractionation to fields limited to the primary site and immediately surrounding tissues. RESULTS: Local tumor control was achieved in all three patients. Two patients subsequently developed metastatic cervical adenopathy; both were controlled with irradiation to the neck. One of these two died of distant metastases. Two patients are alive and well at 13 years and at 26 months. CONCLUSION: We conclude that epithelial lacrimal sac tumors are controllable by radiation therapy and with a good cosmetic result. Poorly differentiated lesions require elective cervical nodal irradiation.

Carcinoma↗
PubMed1994

Secondary hypertension due to renin secreting tumor: a case report.

We report a 20-year-old female with severe hypertension, hypokalemia, hyperaldosteronism and elevated level of plasma renin activity (PRA). The clinical diagnosis of renin secreting tumor of left kidney was made before surgery by the lateralization of plasma renin activity via selective renal venous blood sampling and CT scan of kidney. Prompt normalization of blood pressure and decrease of PRA and aldosterone levels were found after surgical removal of the tumor. The pathological findings showed a juxtaglomerular cell tumor.

Adenocarcinoma↗
PubMed1993

Early extramedullary relapse of acute myelogenous leukemia in bilateral breasts: a case report.

We report a case of a 19-year-old female with acute myelogenous leukemia successfully treated with daunorubicin and Ara-c. Eight months after complete remission, palpable breast masses developed bilaterally. Biopsy and fine needle aspiration of the right mass showed cluster of leukemic cells indicative of extramedullary leukemic relapse. One month after biopsy, the patient's bone marrow showed presence of 90% blast cells. Palpable breast mass may be an early sign of relapse of acute myelogenous leukemia.

Adult↗
PubMed1989

External beam radiotherapy for carcinoma of the prostate.

Five hundred nineteen patients with prostate cancer were seen in the Radiation Oncology Division of the State University of New York (SUNY) Health Science Center, Syracuse, New York, between 1969 and 1981. The results for the 239 patients treated with radical intent are reported here. All patients received 60 to 70 Gy to the prostate with megavoltage beam irradiation; 142 with a small field (10 X 10 cm) 360 degrees rotational technique for Stage A, B, or C disease and 69 with a four-field pelvic brick technique (followed by a boost to the prostate) for Stage A through C and D1 disease. Twenty-eight patients were treated postoperatively for residual disease after radical prostatectomy or for recurrent tumor. The minimum follow-up time was 5 years. Actuarial 5-year and 7-year survival rates for Stage A (n = 34), B (n = 100), C (n = 63), and D1 (n = 14) were 91% and 76%, 86% and 75%, 67% and 40%, and 46% and 36%, respectively. The corresponding 5-year and 7-year relapse-free survival rates were 72% and 65%, 77% and 60%, 46% and 28%, and 38% and 25%. The local tumor control rates at 5 years were 91%, 85%, 77%, and 62% for Stage A, B, C, and D1, respectively. In our experience, there was no significant difference in relapse-free survival rates for patients who underwent transurethral resection (TURP) versus those who did not (67% versus 78% for Stage B [P greater than 0.25] and 38% versus 47% for Stage C [P greater than 0.25], respectively). Also there was no significant difference in relapse-free survival rates between large and small field techniques (64% versus 77% for Stage B [P greater than 0.25] and 56% versus 41% for Stage C [P greater than 0.25], respectively). The 5-year and 7-year actuarial survival rates were 90% and 71%, respectively, for the 15 patients with residual tumor and 58% and 33%, respectively, for the 13 patients treated for postprostatectomy recurrence. Severe complications were documented in only nine patients (3.7%) and mild to moderate complications in 53 patients (22%). Larger fields did not cause a higher rate of complications, although small fields were tolerated better than large fields; the significant acute reaction rate was 27% for large field techniques versus 11% for small field techniques (P greater than 0.01). These results confirm that external beam irradiation is an effective treatment for prostate cancer.

Adult↗
PubMed1989

One-step preparation of competent Escherichia coli: transformation and storage of bacterial cells in the same solution.

We have developed a simple, one-step procedure for the preparation of competent Escherichia coli that uses a transformation and storage solution [TSS; 1 x TSS is LB broth containing 10% (wt/vol) polyethylene glycol, 5% (vol/vol) dimethyl sulfoxide, and 50 mM Mg2+ at pH 6.5]. Cells are mixed with an equal volume of ice-cold 2 x TSS and are immediately ready for use. Genetic transformation is equally simple: plasmid DNA is added and the cells are incubated for 5-60 min at 4 degrees C. A heat pulse is not necessary and the incubation time at 4 degrees C is not crucial, so there are no critical timing steps in the transformation procedure. Transformed bacteria are grown and selected by standard methods. Thus, this procedure eliminates the centrifugation, washing, and long-term incubation steps of current methods. Although cells taken early in the growth cycle (OD600 0.3-0.4) yield the highest transformation efficiencies (10(7)-10(8) transformants per micrograms of plasmid DNA), cells harvested at other stages in the growth cycle (including stationary phase) are capable of undergoing transformation (10(5)-10(7) transformants per micrograms of DNA). For long-term storage of competent cells, bacteria can be frozen in TSS without addition of other components. Our procedure represents a simple and convenient method for the preparation, transformation, and storage of competent bacterial cells.

Cations, Divalent↗
PubMed1989

Stage II seminoma: results of postorchiectomy irradiation.

One hundred forty patients with testicular seminoma were treated at the State University of New York Health Science Center at Syracuse between 1966 and 1985. Disease was classified as stage II in 32 patients (23%): stage IIA in 21 patients and stage IIB in 11 patients. All patients underwent irradiation below the diaphragm after a radical orchiectomy, and 28 underwent planned mediastinal and supraclavicular irradiation. The median follow-up was 8 1/2 years; 24 of 32 patients have been followed up for more than 5 years. Twenty-eight patients remain alive and well; four patients died of intercurrent disease. Two patients developed a recurrent seminoma in the mediastinum; a variant lymphangiographic pattern was shown in these patients, and they were cured. A third patient developed a non-seminomatous "recurrence" in the ipsilateral, unirradiated, inguinal nodes and is well after chemotherapy.

Adult↗