International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Thermoradiotherapy for residual microscopic cancer: elective or post-excisional hyperthermia and radiation therapy in the management of local-regional recurrent breast cancer.
A Phase I/II study was undertaken to investigate the efficacy and side effects of combined hyperthermia and radiation therapy in the management of presumed or known microscopic residual tumors. Between February 1985 and March 1991, 262 fields in 89 patients with local-regional recurrent breast cancer were treated with externally administered hyperthermia and radiation therapy. Thirty-eight fields were treated for microscopic residual disease following excisional biopsy of nodular recurrences and 224 fields were treated electively for areas at high risk for local recurrences adjacent to fields with macroscopic residual disease. ⋯ Parameters in the best five covariate model correlating with the duration of local control included: estrogen receptor status of the initial breast cancer; initial T-stage; time from initial breast cancer to first failure; age at hyperthermia; and concurrent radiation dose (p-value for model less than 0.000001). Six covariate models adding anatomic site of disease, field type, mean minimum temperatures, and mean percent temperatures greater than or equal to 40 degrees C all resulted in improved models. Randomized controlled studies stratifying for these pretreatment parameters are felt warranted to confirm the value of adjuvant hyperthermia in the elective treatment of areas of high risk for local-regional recurrent breast cancer and in fields following surgical excision of recurrent disease, particularly in patients in whom full dose radiation therapy cannot be safely administered.
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Long-term radiation complications following conservative surgery (CS) and radiation therapy (RT) in patients with early stage breast cancer.
The frequency of brachial plexopathy, rib fracture, tissue necrosis, pericarditis, and second non-breast malignancies occurring in the treatment field among 1624 patients with early stage breast cancer treated with conservative surgery and radiation therapy at the Joint Center for Radiation Therapy between 1968 and 1985 is reported. The median follow-up time for survivors was 79 months (range 5-233 months). Brachial plexopathy was related to the use of a third field, the use of chemotherapy and the total dose to the axilla. ⋯ Two of these sarcomas developed in areas of probable match-line overlap. One patient (0.06%) developed an in-field basal cell carcinoma at 42 months. In conclusion, the risk of significant complications following conservative surgery and radiation therapy for early stage breast cancer is low.(ABSTRACT TRUNCATED AT 400 WORDS)
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Int. J. Radiat. Oncol. Biol. Phys. · Jan 1992
Comparative StudyPulsed brachytherapy: the conditions for no significant loss of therapeutic ratio compared with traditional low dose rate brachytherapy.
Pulsed brachytherapy consists of using a stronger radiation source than for traditional low dose-rate brachytherapy, but giving a series of short exposures of 10 to 30 min in every hour, to approximately the same total dose in the same overall time as with the low dose-rate. Calculations based on the linear quadratic model, in which the beta x dose squared component only is assumed to be repairable, and at a monoexponential rate, show that there is no significant loss of therapeutic ratio, defined as tumor damage for a given level of late damage. Some loss of therapeutic ratio would in principle be expected when dose rates are increased, but, in the presently proposed applications, there are so many small pulses (fractions at medium or low dose-rate) that even though repair is not usually complete between them, the relative increase of late damage (in units proportional to log cell kill) is less than 10% more than the increase of tumor damage, except in unlikely conditions that we define. Although these calculations suggest that pulsed brachytherapy should be safe for pulse repetition frequencies up to about 2 hr, using dose rates not exceeding about 3 Gy/hr, we discuss the radiobiological reservations and the limitations of such calculations.