The reverse hockey stick technique: postmastectomy radiation therapy for breast cancer patients with locally advanced tumor presentation or extensive loco-regional recurrence

A combination of photon and electron radiation therapy (RT) fields was devised to treat patients with initial or recurrent breast cancer presentations which extensively involved the chest wall (CW) and/or the axilla. The ipsilateral supraclavicular, infraclavicular, axillary, and lateral CW regions are treated in continuity by anterior and posterior opposed photon beam "reverse hockey stick" fields. The internal mammary and medial chest wall regions are treated by an anterior electron beam field which is tightly junctioned to the photon beam fields. Electron beam energy and thickness of applied bolus are selected so that the electron beam 80% depth isodose curve matches the anterior pleural surface and/or deepest extent of tumor. The goal of treatment is to deliver 4400-5000 cGy to regions at risk of microscopic tumor with local boosts to 6000-7500 cGy to sites of gross disease. Between January 1977, and June 1985, this technique was selectively used in 46 patients, 31 patients with loco-regional tumor recurrence and 15 post-mastectomy patients who initially presented with locally advanced disease. A minimum tumor dose of 4400 cGy was delivered in all except five patients. A diffuse moist skin reaction developed in 31 of the 44 (70%) patients who received at least 3800 cGy. This healed in less than 1 month in all except seven. Frequency of CW diffuse moist skin reaction within the electron beam field was related to the daily applied RT dose. Diffuse moist skin reactions were also noted to be more frequent among patients who had received prior or concurrent Adriamycin. Significant complications included symptomatic arm lymphedema in seven; CW ulcer in two; and acute radiation pneumonitis; steroid-withdrawal radiation pneumonitis, pleuritis, and marked thrombocytopenia in one patient each. With a follow-up of 36-100 months, there was no evidence of loco-regional tumor relapse in 55% of patients treated for recurrent disease and in 73% treated following mastectomy for locally advanced presentations. In summary, we find the reverse hockey stick technique to be a simple, highly reproducible and effective RT approach for postmastectomy breast cancer patients with extensive initial presentation or recurrent disease.

Technique to maintain separation of mandibular loops in interstitial implantation of head and neck tumors

Cancers of the floor of the mouth and lower gingiva are treated by an approach combining external radiation treatment and interstitial implant with Iridium-192 radioisotopes. One technique to administer the dose to these areas is a "loop" technique. A major problem in edentulous patients is that the plastic loops housing the Iridium-192 sources slide out of place along the gum, resulting in loss of ideal spacing. When this occurs, dosimetry for the implant generated from localization films prior to loading does not reflect the distribution of dose delivered. To overcome this problem, we have devised polytetrafluoroethylene (PTFE) spacers which, when used between the loops, maintains their correct spacing. An implant technique and the spacers will be described.

Interstitial implant with interstitial hyperthermia

A Phase I Pilot Study combining interstitial or intracavitary irradiation using 192Ir or 137Cs and interstitial hyperthermia in advanced or recurrent tumors is underway at the City of Hope National Medical Center. Hyperthermia is performed using 0.5 megahertz RF (500 kilohertz) radiofrequency localized current fields. In the implanted volume, a temperature of 41 degrees to 45 degrees C is maintained for 30 to 40 minutes. Hyperthermia is performed prior to irradiation in all patients. All patients had either failed previous conventional treatments, including surgery, chemotherapy and/or radiation therapy, or had advanced malignant tumors which were not felt to be controllable by conventional means. Sixteen lesions were implanted in 15 patients. Of the 16 lesions, 11/16 (68%) achieved complete response, and three had no response or recurred locally. The six patients (100%) receiving interstitial implant and hyperthermia as the primary therapy achieved complete response. Normal tissue complications were minimal. Range of response was three to 13 months. Interstitial thermoradiotherapy appears to be a safe and promising mode of therapy in advanced or recurrent accessible malignant tumors.

DNA repair synthesis in minimally stressed human lymphocytes

We have estimated the rate of unscheduled DNA synthesis (UDS) in human lymphocytes from measurements of tritiated thymidine incorporation into double-stranded DNA (ds-DNA) during incubation of cells in vitro. Cells were not subjected to stresses except those associated with careful handling, or in certain experiments, mild heating or treatment with phytohaemagglutinin (PHA). Contribution of scheduled DNA synthesis (SDS) to incorporation was reduced by inhibiting replication and separating freshly replicated single-stranded DNA from repaired ds-DNA by chromatography. By increasing the incubation temperature, which decreases SDS and increases UDS, the residual contribution of scheduled DNA synthesis to thymidine incorporation into ds-DNA was estimated. Effects of increasing the number of cells in S-phase by phytohaemagglutinin were also investigated. Results suggest that: the rate of unscheduled DNA synthesis is about 500 +/- 100 thymidine molecules incorporated per cell per hour; a temperature-sensitive process, probably hydrolysis of DNA, contributes much of the damage repaired by UDS; background ionizing radiation contributes little to the damage; and damage caused by DNA hydrolysis is repaired much more efficiently than lethal damage caused by ionizing radiation. Large increases in incorporation into ds-DNA occurred when cells were stimulated with PHA.