Secondary tumors in cancer patients after therapy.

Forty-five thousand three hundred thirteen patients treated in our Institute during the period 1949-1982 were retrospectively analyzed in regard to the appearance of secondary tumors after therapy. Eighty-seven (0.19%) tumors were found, 71 (81.6%) being secondary and 16 (18.4%) simultaneous. Fifty-one (71.8%) tumors were lymphoid, 20 (28.1%) nonlymphoid. Thirty-seven (52.1%) tumors appeared after radiotherapy, 13 (18.3%) after chemotherapy alone. Secondary tumors appeared mostly after 6 years. The prevalence of lymphoid secondary tumors may be explained as a compensatory proliferation of surviving cells progressing to neoplasia. Cytostatics and ionizing radiation as both the initiators and the promoters of malignancy, have besides person's susceptibility a triggering function. From these aspects before any treatment is started all possible carcinogenic factors should be taken into consideration and less carcinogenic procedures with keeping up a full effectiveness should be chosen.