Timing and sequencing of chemoradiotherapy.
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Clinical Trials as Topic↗
Biomedical subjects
D J Haraf
Publications and source records attributed to D J Haraf.
A phase I trial of concomitant chemoradiotherapy with cisplatin dose intensification and granulocyte-colony stimulating factor support for advanced malignancies of the chest.
UNLABELLED: Concomitant chemoradiotherapy with cisplatin and combination chemotherapy in the neoadjuvant setting have both shown promising results. PURPOSE: To identify a locally and systemically active concomitant chemoradiotherapy regimen incorporating high-dose cisplatin, interferon alfa-2a (IFN), fluorouracil (5-FU), hydroxyurea (HU) and radiotherapy. METHODS: Phase I cohort design establishing the maximal tolerated dose (MTD) of cisplatin with and without granulocyte colony stimulating factor (GCSF). For the first six dose levels, a 4-week cycle consisted of escalating doses of cisplatin during weeks 1 and 2, IFN (week 1), and 5-FU and HU (week 2) with single daily radiation fractions of 200 cGy during days 1-5 of weeks 1-3 and no treatment in week 4. When dose-limiting neutropenia was encountered. GCSF was added during weeks 1, 3, and 4. Finally, to decrease esophagitis, the radiotherapy schedule was altered to 150 cGy twice daily during weeks 1 and 2, followed by a 2-week break (level 7). RESULTS: Forty-nine patients with refractory chest malignancies were treated. The MTD of this regimen without GCSF was cisplatin 50 mg/m2 in weeks 1 and 2, IFN 5 million Units (MU)/m2 per day on days 1-5 in week 1, 5-FU 800 mg/m2 per day for 5 days by continuous infusion, and HU 500 mg every 12 h for 11 doses during week 2. The addition of GCSF during weeks 1, 3, and 4 allowed for escalation of cisplatin to 100 mg/m2 during weeks 1 and 2, with a decreased dose of IFN at 2.5 MU/m2 per day to avoid renal toxicity. Dose-limiting toxicity (DLT) included severe neutropenia, thrombocytopenia, and esophagitis in 5 of 13 patients. Increased thrombocytopenia in patients receiving GCSF was not observed. During hyperfractionated radiotherapy (level 7) chemotherapy doses were as above except for a reduction of 5-FU to 600 mg/m2 per day. While severe esophagitis was reduced, grade 4 thrombocytopenia became more prevalent and was seen in 6 of 7 patients. In-field tumor responses were observed in 17 of 28 evaluated patients with non-small-cell lung cancer. The median times to progression and survival were 4 and 6 months, respectively. When only patients with all known disease confined to the radiotherapy field were considered the corresponding times were 6 and 15 months, respectively. Most treatment failures occurred outside of the irradiated field. CONCLUSIONS: (1) This intensive multimodality regimen can be given with aggressive supportive care incorporating GCSF. The recommended phase II doses for a 4-week cycle are cisplatin 50 mg/m2 week 1, and 100 mg/m2 week 2, IFN 2.5 MU, HU 500 mg every 12 h x 11 and 5-FU 800 mg/m2 per day with single fraction radiotherapy during weeks 1-3 and GCSF during weeks 1, 3, and 4. (2) GCSF can be safely administered and provides effective support of neutrophils when administered simultaneously with IFN, cisplatin, and chest radiotherapy. (3) There is synergistic renal toxicity when high doses of IFN and cisplatin are given together. (4) Hyperfractionated radiotherapy decreases the severity of esophagitis but increases thrombocytopenia. (5) Although highly toxic, response rates, time to progression and survival figures with this regimen are encouraging and support its investigation in the phase II setting.
Adult↗
Intensive multimodality therapy for carcinoma of the esophagus and gastroesophageal junction.
BACKGROUND: We designed a trial of intensive multimodality therapy for carcinoma of the esophagus and gastroesophageal junction to assess tumor response and operability after neoadjuvant chemotherapy and to determine the impact of trimodality therapy on longterm survival. METHODS: Thirty-two patients with resectable (clinical stage IIa, n = 17; IIb, n = 1; III, n = 14) squamous cell cancer (n = 15) or adenocarcinoma (n = 17) were treated with neoadjuvant chemotherapy (cisplatin, 5-fluorouracil, leukovorin), resection, and postoperative chemoradiotherapy (hydroxyurea, 5-fluorouracil; 50-66 Gy). RESULTS: Use of neoadjuvant chemotherapy yielded the following results: a measurable clinical response in 22 patients, stable disease in eight patients, disease progression in one patient, and death in one patient. Thirty-one patients underwent resection, with the following results: two operative deaths (6.5%) and nonfatal morbidity in 17 (59%); the median hospital stay was 13 days. Pathologic staging was stage 0, n = 1; I, n = 2; IIa, n = 11; IIb, n = 5; III, n = 7; and IV, n = 5. Postoperative chemoradiotherapy was completed in 23 patients with one death, for an overall treatment-related mortality rate of 12.5% (four of 32). At a mean follow-up of 22.5 months, median survival is 19.7 months and 14 patients are alive and disease free. CONCLUSIONS: Neoadjuvant therapy for cancer of the esophagus and cardia results in good tumor response. Esophagectomy in this setting can be accomplished with acceptable morbidity and mortality. Results of an interim analysis of survival are encouraging and suggest that further investigation of this regimen is warranted.
Adenocarcinoma↗
Induction chemotherapy followed by concomitant chemoradiotherapy for advanced head and neck cancer: impact on the natural history of the disease.
PURPOSE: To determine survival rates and the pattern of failure in head and neck cancer patients treated with induction chemotherapy, limited surgery and concomitant chemoradiotherapy. PATIENTS AND METHODS: Three cycles of induction chemotherapy with cisplatin, fluorouracil (5-FU), leucovorin, and interferon alfa-2b (PFL-IFN) were followed by optional surgery, and seven or eight cycles of 5-FU, hydroxyurea, and concurrent radiation for 5 days (FHX) for a total radiation dose of 65 to 75 Gy. Surgical resection was performed with the intent to spare organ function. RESULTS: Seventy-one patients were treated at three institutions. Sixty-five patients (91%) had stage IV disease with N2/3 in 46. Thirty-three patients (51%; 95% confidence interval, 39% to 63%) achieved a clinical complete response (CR) to PFL-IFN. Local therapy consisted of surgery in 37 and/or FHX in 55 patients. With a median follow-up duration of 37 months, there have been 20 recurrences (15 local, four distant, and one both local and distant), and 29 deaths, 15 in patients with disease progression and 14 not directly related to the primary tumor. Four patients have developed second malignancies. At 3 years, 69% (+/- 6%) are progression-free and the overall survival rate is 60% (+/- 6%). Toxicity of PFL-IFN included severe or life-threatening mucositis (54%) and myelosuppression (60%). Five patients died of toxicity. During FHX, 70% of patients had grade 3 or 4 mucositis. CONCLUSION: PFL-IFN is highly active, producing clinical CRs in 51% of patients, and, when followed by FHX, resulting in high local and distant control and overall survival rates. Second malignancies and intercurrent medical disease emerge as major risks to long-term survival. In view of the high toxicity and long treatment duration, further modifications of this approach are required.
Adolescent↗
Surgical management of the head and neck cancer patient following concomitant multimodality therapy.
The simultaneous use of chemotherapy and radiotherapy (concomitant therapy) has exceptional promise in the treatment of head and neck cancer. In this limited review, seven head and neck cancer patients who underwent prior concomitant therapy and subsequent surgery developed wound-healing complications that were delayed (22-day average) in onset. Paranasal sinus and base of skull operations had less significant wound morbidity than those cases requiring simultaneous transgression of the neck and upper aerodigestive tract. The use of arterialized flaps did not in itself prevent wound breakdown. The formation of controlled fistulae, delay of reconstruction, and avoidance of simultaneous neck and upper aerodigestive tract entry are important considerations in avoiding wound-healing complications after concomitant therapy. In this select group of patients, surgery should be approached with extreme caution and conservatism.
Adult↗
The role of paclitaxel in the treatment of head and neck cancer.
Current chemotherapeutic approaches to recurrent head and neck cancer have routinely yielded response rates of 10% to 30% (for single agents) and 30% to 50% (for combination chemotherapy). However, median survival times for patients with metastatic and/or recurrent disease have stagnated at around 6 months since the 1970s. The investigation of new drugs and treatment approaches thus continues to be a high priority. One such agent, paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), has shown good single-agent activity and is also believed to potentiate the effects of radiation therapy in patients with head and neck cancer. We have focused on the addition of paclitaxel to the previously established combination of 5-fluorouracil, hydroxyurea, and radiation therapy. The study goals are to establish the maximum tolerated dose and dose-limiting toxicity of paclitaxel when added to this combination as a 5-day continuous infusion on a biweekly schedule. Preliminary results of this ongoing study have demonstrated activity in patients with poor-prognosis head and neck cancer. Major dose-limiting toxicities have consisted of neutropenia and mucositis, and definition of a recommended phase II dose is in progress.
Adult↗
Time-dose relationship for local tumor control following alternate week concomitant radiation and chemotherapy of advanced head and neck cancer.
PURPOSE: To analyze the time-dose relationship for local control of disease in patients with advanced head and neck neoplasms enrolled in two sequential Phase I dose escalation studies in which concomitant chemotherapy and radiotherapy were delivered on an alternate week schedule (i.e., 1 week of concomitant therapy alternated with 1 week of rest). METHODS AND MATERIALS: From 1986-1988, 65 patients were enrolled in two Phase I clinical trials. In trial one, 5-fluorouracil and hydroxyurea were administered concomitantly with radiation on an alternate week schedule (39 pts). In trial two, cisplatin was added to 5-fluorouracil and hydroxyurea (26 pts). Fifty-seven patients were evaluable for local control, including 26 patients who had failed prior local therapy and were retreated (group A), and 31 patients who had received no prior local therapy (group B). The median dose of RT and the median duration of therapy were 59.7 Gy and 12 weeks for group A, and 70.2 Gy and 14 weeks for group B, respectively. The biological effective dose of radiation therapy (RT) was calculated using the equation based on the linear quadratic model as proposed by J. Fowler. Univariate and multivariate logistic regression analyses were performed to evaluate prognostic factors for local control. RESULTS: Six of 26 patients in group A and 30 of 31 patients in group B had local control of disease. The 2-year Kaplan-Meier local failure rates were 84% for group A and 4% for group B, respectively. Despite the doubling of treatment duration compared to conventional daily radiotherapy and the low biological equivalent dose calculated (median biological equivalent dose for patients with local control of disease were 50.3 Gy and 48.8 Gy in groups A and B, respectively), local control was achieved in 5/17 patients in group A and 30/31 patients in group B who received RT dose of 59.4 Gy or higher. In multivariate logistic regression analysis, the only significant predictor for local control of disease was RT dose (p = 0.004). Treatment duration, chemotherapy dose intensities, age, and performance status were not significant variables. Decreasing the RT dose by 10 Gy would increase the rate of local failure by 24%. CONCLUSION: Our data suggest that prolongation of treatment duration to twice the normal duration of conventional once-a-day radiotherapy does not result in loss of local control when aggressive cell-cycle specific chemotherapy is given concomitantly with radiotherapy. The usual time-dose relationship based on RT alone does not appear to be applicable when concomitant chemotherapy is added. The clinical significance of biological equivalent dose calculation based on radiotherapy alone is unclear when chemotherapy is given with radiation.
Adult↗
Concomitant chemoradiotherapy for non-small cell lung cancer.
Concomitant chemoradiotherapy represents an investigational approach to the treatment of locoregionally advanced non-small cell lung cancer. The theoretical rationale, and clinical experience are reviewed in brief. Clinical trials conducted at the University of Chicago are summarized.
Antineoplastic Combined Chemotherapy Protocols↗
Laparoscopic pelvic lymph node dissection: a review of 103 consecutive cases.
Laparoscopic pelvic lymph node dissection is a recently introduced technique for the surgical evaluation of the regional pelvic lymph nodes in genitourinary malignancies. We report the results of a laparoscopic pelvic lymph node dissection performed on 103 consecutive patients for staging of clinically localized prostatic, bladder and penile carcinomas. In 20 patients (group 1) the adequacy of the laparoscopic pelvic lymph node dissection was evaluated with a subsequent open dissection. In this group 87 to 95% of the lymph nodes within a modified template could be reliably removed laparoscopically. In 73 patients (group 2) laparoscopic pelvic lymph node dissection was performed as a solitary operation. Mean hospitalization was 1.6 +/- 2.4 days, while postoperative narcotic requirements were minimal. Mean operative time for bilateral laparoscopic pelvic lymph node dissection was 156 +/- 41.2 minutes. The overall complication rate in these 2 groups was 13.5%. Group 3 includes 10 patients (9.7% of the total) in whom laparoscopic pelvic lymph node dissection was unsuccessful. The minimally invasive surgical techniques of laparoscopic pelvic lymph node dissection seem to provide adequate staging accuracy in patients with genitourinary neoplasms. The complication rate and recovery period appear to be decreased relative to those for open surgical lymphadenectomy.
Adenocarcinoma↗
Intensified concomitant chemoradiotherapy with and without filgrastim for poor-prognosis head and neck cancer.
PURPOSE: We previously demonstrated high locoregional control rates in patients with poor-prognosis head and neck cancer using fluorouracil (5-FU), hydroxyurea (HU), and concomitant radiotherapy (FHX). In two trials reported here, we added cisplatin with and without granulocyte colony-stimulating factor (G-CSF) to 5-FU, HU, and concomitant radiotherapy. PATIENTS AND METHODS: Eligible patients had failed to respond to prior local therapy (group 1); previously untreated patients with unresectable and/or metastatic disease and a projected 2-year survival rate less than 10% were also eligible (group 2). Chemoradiotherapy consisted of 1.8 to 2.0 Gy on days 1 to 5 with simultaneous infusional 5-FU at 800 mg/m2/d and HU administered every 12 hours for 11 doses at escalating doses. Cisplatin was administered at 100 mg/m2 during every other cycle. Cycles were repeated every 14 days until completion of radiotherapy. In study 2, G-CSF was added on days 6 to 13 at 5 micrograms/kg/d. RESULTS: Acute and cumulative myelosuppression limited the feasibility of adding cisplatin to FHX without G-CSF. G-CSF allowed for escalation of HU to 1 g orally every 12 hours without dose-limiting acute toxicity during cycles 1 and 2. Dose-limiting cumulative toxicity consisted of severe or life-threatening myelosuppression and mucositis. To decrease total treatment duration and, thus, cumulative toxicity, a hyperfractionated radiation therapy schedule was investigated using the established chemotherapy doses with 1.5 Gy twice daily on days 1 to 5 (75 Gy over five treatment cycles). No increase in acute toxicities was seen; cumulative toxicities remained frequently severe or life-threatening. Thirty-eight of 45 assessable patients responded. The median survival duration was 12 months for both groups. Median time to treatment failure was 8 months for group 1 and has not been reached for group 2. At 1 year, local control rates were 74% and 91% for groups 1 and 2, respectively. CONCLUSION: The addition of cisplatin to 5-FU, HU, and concomitant radiotherapy is feasible using G-CSF. The high locoregional control rate and failure-free interval justify further investigation of this regimen in previously untreated patients.
Adult↗
Varying levels of radioprotection from the effects of JANUS neutrons in repair-deficient xrs-5 hamster cells treated with azacytidine.
A series of cell lines have been generated from the radiation-sensitive Chinese hamster ovary line xrs-5 by treatment with azacytidine. Several of these lines have been shown to be resistant to gamma radiation. Survival curves have been generated for several of these lines and the parental lines after exposure to 0 to 5 Gy of JANUS neutrons in the presence or absence of a 30-min pretreatment with the aminothiol radioprotector WR-1065. These studies were performed to determine whether the parental xrs-5 cell line was radioresistant to exposure to JANUS neutrons and whether reversion to a neutron-resistant phenotype correlated with recovery of aminothiol radioprotection. Exposure to 4 mM WR-1065 enhanced survival after exposure to neutron radiation for most "revertant" lines, although the increase in survival varied. The xrs-5 cell line was sensitive to JANUS neutrons and showed no protection by WR-1065. These data indicate that xrs-5 cells are also sensitive to neutron radiation, that azacytidine-induced revertants for gamma-ray survival demonstrate the wild-type phenotype for survival after neutron exposure, and that the gene product that is defective is responsible for repairing only a small portion of neutron-induced damage.
Animals↗
A phase II study of cisplatin, 5-fluorouracil, and leucovorin augmented by vinorelbine (Navelbine) for advanced non-small cell lung cancer: rationale and study design.
In a randomized phase II study by the Cancer and Leukemia Group B, the cisplatin/5-fluorouracil/leucovorin (PFL) combination produced a 29% response rate in advanced, unresectable non-small cell lung cancer. Vinorelbine (Navelbine; Burroughs Wellcome, Co, Research Triangle Park, NC; Pierre Fabre Médicament, Paris, France), a semisynthetic vinca alkaloid, has also demonstrated single-agent activity in this disease. Therefore, a phase I-II study was designed to investigate the addition of vinorelbine in escalating doses to the PFL combination. The objectives of this study were to establish the maximum tolerated dose of vinorelbine in combination with PFL, and to define the overall response rate in a cohort of patients treated with the maximum tolerated dose. The regimen consisted of vinorelbine in escalating doses starting at 20 mg/m2/d intravenously on days 1 and 5, followed by leucovorin 100 mg orally every 4 hours on days 1 to 5,5-fluorouracil 800 mg/m2/d intravenous continuous infusion days 2 to 5 (96 hours), and cisplatin 100 mg/m2 intravenously 12 to 24 hours after administration of the first dose of vinorelbine. Cycles were repeated every 3 weeks. No dose-limiting toxicity was observed in the first five patients treated with the initial vinorelbine dose. Increasing the dose of vinorelbine to 25 mg/m2 in a second cohort of two patients, however, resulted in grade 4 granulocytopenia in both, and grade 4 diarrhea in one. It was concluded that this dose level was not feasible. During a preliminary analysis, one complete response and three partial responses were observed in 16 patients evaluated; one of these patients had a pathologic complete remission. This early analysis indicates activity for the regimen.
Adult↗
Radiation therapy in head and neck cancer: indications and limitations.
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Head and Neck Neoplasms↗
Escalating doses of interferon alpha-2A with cisplatin and concomitant radiotherapy: a phase I study.
In this phase I study, we added escalating doses of interferon-alpha 2A (IFN) to cisplatin and twice-daily radiotherapy based on the following rationale. Radiation enhancement has been shown for both interferon and cisplatin; in addition, potentiation of the cytotoxic activity of cisplatin by interferon has been demonstrated. A total of 48 patients with advanced solid tumors were treated with radiotherapy in 2 daily fractions of 125 cGy plus cisplatin at 8-10 mg/m2 per day delivered on 3 different schedules (continuous infusion, daily short-term infusion, and single short-term infusion of 50 mg/m2). IFN was injected s.c. 2 h preceding the first daily fraction of radiation. IFN doses ranged from 0 to 5.0 x 10(6) U/m2 per day. All therapy was given over 5 days of every other week until completion of the radiotherapy. Treatment at all dose levels was well tolerated during cycles 1 and 2, with no instance of acute grade 3 or 4 toxicity being noted. However, cumulative myelosuppression in patients receiving more than two treatment cycles was seen at all dose levels and was attributed to the repeated administration of cisplatin. Alteration of the cisplatin schedule did not allow for further dose escalation of cisplatin. Our recommended doses are cisplatin given at 8 mg/m2 per day as a continuous infusion with IFN at 5.0 x 10(6) U/m2 per day. Among 24 patients with non-small-cell lung cancer, 2 had a complete response, 9 had a partial response, and 7 had stable disease. We conclude that this concomitant cisplatin-IFN-radiotherapy regimen is feasible. Activity was seen in non-small-cell lung cancer, and further studies of this regimen in that disease appear indicated.
Adult↗
Favorable long-term survival following induction chemotherapy with cisplatin, fluorouracil, and leucovorin and concomitant chemoradiotherapy for locally advanced head and neck cancer.
BACKGROUND: The majority of patients with head and neck cancer die of locoregional recurrence of disease following surgery and/or radiotherapy. PURPOSE: Our purpose was to administer induction chemotherapy, perform surgery, and administer concomitant chemoradiotherapy in rapid sequence and to evaluate their impact on locoregional and distant tumor control. METHODS: Sixty-four patients with previously untreated, locoregionally advanced head and neck cancer received two cycles of cisplatin, bleomycin, and methotrexate (PBM) (33 patients) or cisplatin, fluorouracil (5-FU), and leucovorin (PFL) (31 patients). PFL was given to patients who were unable to receive bleomycin. Local therapy consisted of surgery and/or concomitant chemoradiotherapy with 5-FU, hydroxyurea, leucovorin, and radiotherapy (FHX-L), all administered every other week. RESULTS: Complete and overall induction response rates were 21% and 79%, respectively, for PBM and 29% and 81%, respectively, for PFL. At completion of local therapy, 81% of the patients were disease-free. With a median follow-up of 35 months, the median survival and time to progression are 22 and 17 months, respectively, for PBM and have not been reached for PFL. Locoregional recurrence of disease is 30% for PBM and 26% for PFL. Distant disease progression is 24% for PBM and only 3% for PFL. CONCLUSIONS: The sequencing of induction chemotherapy and concomitant chemoradiotherapy is feasible and results in a high local control rate and in an encouraging survival rate with PFL. The high distant failure (i.e., outside the head and neck area) rate of PBM suggests insufficient systemic activity for that regimen. IMPLICATIONS: Concomitant FHX-L chemoradiotherapy may improve regional control rates of advanced head and neck cancer. Effective systemic therapy may be needed to control systemic micrometastases. PFL, but not PBM, appears to be suitable to accomplish that goal.
Antineoplastic Combined Chemotherapy Protocols↗
5-Fluorouracil, leucovorin, hydroxyurea, and escalating doses of continuous-infusion cisplatin with concomitant radiotherapy: a clinical and pharmacologic study.
Cisplatin (CDDP), 5-fluorouracil (5-FU), and hydroxyurea (HU) have individually demonstrated activity against several solid tumors, act synergistically with each other in vitro, and may act as radiation sensitizers. Therefore, we designed a phase I study to determine the maximally tolerated dose of cisplatin as given in addition to our previously described combination of 5-FU, HU, and concomitant radiotherapy (XRT). Patients exhibiting advanced solid tumors requiring palliative XRT were eligible. The regimen consisted of 1 g HU given p.o.b.i.d. on days 1-5, 600 mg/m2 5-FU given i.v. daily by continuous infusion (c.i.) on days 1-5, escalating doses of cisplatin starting at 10 mg/m2 daily given by c.i. on days 1-5, and involved-field XRT carried out on days 1-5. The cycle was repeated every 14 days until the target XRT dose had been reached. In all, 19 patients were entered at the first dose level, and cumulative grade 3-4 myelosuppression was seen in 16 subjects. As no dose escalation was feasible, the chemotherapy was subsequently altered by using the above regimen for cycles 1, 3, 5, and 7 and substituting the less myelosuppressive regimen of 1 g HU given p.o.b.i.d. on days 1-5, 400 mg/m2 5-FU given i.v. daily by c.i., and 100 mg leucovorin given p.o.4 h on days 1-5 for cycles 2, 4, and 6. On this alternating program, 28 patients were treated with escalating doses of CDDP. The dose-limiting toxicity was again myelosuppression, which was prohibitive at a CDDP dose of 20 mg/m2 daily. In the final phase of the protocol, 30 subjects were treated with the above alternating-cycle regimen at a CDDP dose of 20 mg/m2 daily and a decreased HU dose of 500 mg p.o.b.i.d. in an attempt to circumvent the myelosuppression associated with this dose of CDDP. Although severe acute toxicity (cycles 1 and 2) was observed less frequently, cumulative toxicity (all cycles) remained pronounced. The other major toxicity encountered was mucositis, which was particularly pronounced in patients receiving radiation to the head and neck and following leucovorin-containing cycles. Plasma concentrations of free platinum did not correlate with the CDDP dose, possibly due to the narrow range of doses given. Pharmacodynamic modeling demonstrated that the CDDP dose and the HU dose were associated with leukopenia. Antitumor activity was demonstrated in a number of solid tumors particularly non-small-cell lung cancer and head and neck cancer.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Reversion of radiosensitivity in azacytidine-treated XRS5 cells does not result in full radioprotection by WR-1065.
A series of cell lines were previously generated from the radiation sensitive Chinese hamster ovary line xrs5 after treatment with azacytidine. Six of these lines have been examined for their resistance to killing by 0 to 20 Gray of 60Co gamma rays and the amount of radioprotection afforded by treatment with the drug 2-[(aminopropyl)amino]ethanethiol (WR-1065). As xrs5 cells have lost the ability to be protected by WR-1065, studies were performed to determine whether reversion to radio-resistance correlated with recovery of aminothiol radioprotection. Treatment of azacytidine-treated, radiation sensitive and resistant cells with four millimolar WR-1065 30 minutes prior to irradiation enhanced survival after exposure to gamma radiation, although the enhancement in survival was less than for wild type Chinese hamster ovary K1 cells. The data suggest that there is not an absolute linkage between recovery of gamma ray radiation resistance and protection by WR-1065 and other factors, such as chromatin organization, must play a role.
Animals↗
A dosimetric study comparing three-, four-, and six- field plans for treatment of carcinoma of the prostate.
We present a three-dimensional dosimetric analysis of 3-, 4-, and 6-field plans using 24 MV photon beams for treatment of carcinoma of the prostate. We compare isodose distributions on a transverse plane through the center of the target as well as differential and integral dose volume histograms for the target and critical structures, respectively. An extensive study on a representative case led to the development of a technique where two complementary 3-field daily plans deliver the same daily target dose as the standard 4-field box while affording sparing of the bladder and rectum similar to that achieved with a 6-field plan. This technique was shown to yield the same results on a sample of four additional patients representing a range of target and patient sizes. We conclude that the combined two-day, 3-field method for treatment of the prostate may be a better choice than the standard 4-field box or the 6-field daily plan for dose escalation studies.
Humans↗