Continuing increased risk of second cancer in long‐term testicular cancer survivors after treatment in the cisplatin era

Using complete information on total treatment burden, this population‐based study aimed to investigate second cancer (SC) risk in testicular cancer survivors (TCS) treated in the cisplatin era. The Cancer Registry of Norway identified 5,625 1‐year TCS diagnosed 1980–2009. Standardized incidence ratios (SIRs) were calculated to evaluate the total and site‐specific incidence of SC compared to the general population. Cox regression analyses evaluated the effect of treatment on the risk of SC. After a median observation time of 16.6 years, 572 TCS developed 651 nongerm cell SCs. The SC risk was increased after surgery only (SIR 1.28), with site‐specific increased risks of thyroid cancer (SIR 4.95) and melanoma (SIR 1.94). After chemotherapy (CT), we observed 2.0‐ to 3.7‐fold increased risks for cancers of the small intestine, bladder, kidney and lung. There was a 1.6‐ to 2.1‐fold increased risk of SC after ≥2 cycles of cisplatin‐based CT. Radiotherapy (RT) was associated with 1.5‐ to 4.4‐fold increased risks for cancers of the stomach, small intestine, liver, pancreas, lung, kidney and bladder. After combined CT and RT, increased risks emerged for hematological malignancies (SIR 3.23). TCS treated in the cisplatin era have an increased risk of developing SC, in particular after treatment with cisplatin‐based CT and/or RT. What's new? Long‐term survival to 15 years among germ cell testicular cancer survivors treated in the cisplatin era, marked by the introduction of cisplatin in the late 1970s, generally has been excellent. Beyond 20 years, however, survival rates decline. In this analysis of data on Norwegian men diagnosed with testicular cancer between 1980 and 2009, an increased overall risk for nongerm cell second cancer was detected among survivors, despite treatment. Risk was elevated in particular beyond 10 years of follow‐up after cisplatin‐based chemotherapy or radiotherapy. Despite reduced treatment intensity, two or more cycles of cisplatin‐based chemotherapy was associated with continuing increased second cancer risk.