Incidence and Survival of Patients Who Developed Limited-Stage Small Cell Lung Cancer after Successful Treatment of a Previous Cancer

Longer survival made possible by improvements in cancer detection and treatment increases the risk of developing a subsequent malignancy. Although the type of the primary malignancy would be expected to affect the outcome of treating second malignancies, clinical information on patients who develop limited-stage small cell lung cancer (LS SCLC) is not well known. Our aim here was to evaluate the incidence of LS SCLC after treatment of other types of cancer and to compare survival between those patients and patients with limited LS SCLC and no other malignancies. All patients had LS SCLC that had been treated with 45 Gy or higher dose of radiotherapy by daily or twice daily fractionated irradiation and chemotherapy at a single institution in 1985-2012; the SCLC was considered a metachronous second malignancy if it appeared more than 2 years after the diagnosis of primary malignancy of a different histologic type. Among 576 patients analyzed, 50 (8.7%) had metachronous second LS SCLC and 526 patients had LS SCLC and no other malignancies. No differences were found between two groups in year of diagnosis, sex, age, race, smoking pack-years, or treatment for the SCLC (radiation dose, and receipt and timing of chemotherapy [concurrent vs. sequential or induction]). The median follow-up times were 14.5 months (range 0.2–175.1) for patients with metachronous second LS SCLC and 15.5 months (range 0.1–266.4 months) for patients with LS SCLC and no other malignancies. Among the 50 patients with metachronous second LS SCLC, only 1 patient did not smoke. The median follow-up time from the primary cancer to the metachronous SCLC was 89.5 months (range 24.61-1131.78 months); the primary cancer types were breast (n=12), colon (n=5), bladder (n=4), uterus (n=4), melanoma (n=4), lymphoma (n=4), NSCLC (n=3), prostate (n=3), vocal (n=2), kidney (n=2), leukemia (n=2), stomach (n=1), urethra (n=1), cervix (n=1), epiglottis (n=1) and axillary lymph node (the precise location of the node was unknown) (n=1). Overall survival rates were no different for patients with metachronous second LS SCLC and those with LS SCLC and no other malignancies (5-year rates 36.0% vs. 42.7%; log-rank p=0.14). Long-term survivors after successful treatment of cancer, particularly smokers, should be monitored carefully for the development of second malignancies such as SCLC, as such second cancers can also be successfully treated. Investigation of the second malignancies were within previously irradiated areas is underway.