Secondary tumors in cancer patients after therapy

Forty-five thousand three hundred thirteen patients treated by 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 mostly appeared 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, in addition to sensitizing, a triggering function. From these aspects, before any treatment is started all possible carcinogenic factors should be taken into consideration and less carcinogenic procedures should be chosen while maintaining full efficacy. (author)