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The paper reports on the use of carbon dioxide and Nd:YAG lasers for palliation of locoregional breast cancer recurrences. On the basis of three case reports, pros and cons of laser assisted treatment of loco-regionally recurrent breast cancer are discussed. A carbon dioxide--Nd:YAG combination therapy is proposed as the method best suited. The preliminary results indicate that laser palliation of local relapse and soft tissue metastases might enlarge the therapeutic spectrum.

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RESUMEN

Between 1960 and 1975, 53 mammary carcinomas have been observed in a collective of 15000 women a part of whom, comprising finally 80 per cent, was free from troubles (annual prophylactic examination for breast cancer). Of these 53 cases were available two up to eleven preceding mammographic series made within an observation period of 0.2 to eleven years. A "mean growth curve" was obtained empirically, based on 163 mammographic tumor measurements with tumor sizes between 2 mm and 60 mm. In the course of a development period between two and eleven years, 33 per cent of the carcinomas were seen to accelerate their further growth in comparison with the initial value; 66 per cent revealed an increasing slow-down of growth, and all tumors showed considerable changes in their growth rates. Mammary carcinomas altogether continually decelerated their growth as measured by the duplication time of the tumor volume from Tv = 309 days on the average up to an average of Tv = 381 days after two through eleven years. The mean growth curve exhibited an exponential shape which was completed by biomathematical methods and can be described by means of a Power function. It corresponds well to the rate of incidence of the mammary carcinoma which shows an identical rise in relation to increased old age. The medium growth time from a primary cancerous cell with ten micron in size up to the tumor 2 mm in diameter may be estimated biomathematically only and amounts to ten or twenty years with 23 duplication periods. The further average growth rate between the tumor sizes of two and ten millimeter, stages which can be diagnosed roentgenologically, was empirically six years; the most quickly growing tumor needed almost two years. For the purpose of early cancer detection (tumor size below 10 mm, lymph nodes histologically free from metastases), the serial mammography to be performed every 18 months or two years is the only technique which provides utilizable early recognition marks and besides does allow a simple judgement. Solely the symptoms "suspect desification, partly spiculated" in sixty per cent and "typical cancerous microcalcification" in forty per cent have been observed as the earliest signs. The reliability ("certainty") of mammography is frequently overestimated (false negative rate: 7 to 18%) and should be quoted only for collectives where control mammographies have been made over a period of five or ten years. Roentgenological controls of alterations below three millimeter in size and without an indication for biopsy ought to be performed within six months, and still sooner in case of larger alterations. It is not possible earlier than after five or ten years to judge of the radicality of a therapy, as spread cancerous cells, on he average, reveal similar growth rates as does the primary tumor.

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For all centers performing gynecological contact irradiation the use of afterloading techniques is urgently required, since they eliminate any radiation exposure to the personnel. The radio-therapist may position and control the empty applicators still free from radiation withoug haste. This procedure diminishes the occurrence of overdosages and underdosages. The care for the patients is possible without radiation exposure, and the morbidity of contact therapy can be reduced by occasional mobilization of the patient, the applicator without sources remaining at its place. The fully automatic apparatus "Curietron" using cesium-137 sources (0.662 MeV gamma emission, half-life period 26.6 years) with an equivalent source activity (factor 2.6) yields the dose distribution demanded in the gynecologic field which in practice is identical to that of Ra-226 (medium gamma emission 1 MeV, half-life period 1620 years). With similar dose distribution, a biological and therapeutical effect alike to Ra-226 may be expected from Cs-137. In comparison with Ra-226, the following advantages of Cs-137 may be mentioned: Lower half-value thickness of 5.5 mm lead (low expenses for radioprotection), less danger with handling (no emanation of radioactive gases), and lower contamination risks in case of breaking. The measured dose distributions at equivalent source activity and similar geometry of the applicators revealed the possibility with regard of all techniques of gynecologic irradiation utilized in our field of arriving at similar relative and absolute dose distributions by means of the Cs-137 afterloading technique. Whilst short-term afterloading irradiation with highly active sources, their radiobiological effectiveness being not yet ascertained, has to be tested at appropriate scientific centers, it is necessary to demand afterloading techniques with dosages and duration of irradiations approved over decades for all centers of gynecological contact therapy because of radiation protection.

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