Chemotherapy linked to lower risk of second testicular cancer

Among men with unilateral testicular cancer, use of cisplatin-based chemotherapy was associated with a 45% reduction in the risk of developing a second testicular cancer versus use of surgery-alone.¹

Results from a population-based cohort study showed that 3.2% of men who received chemotherapy developed a second cancer, compared with 5.4% of men who only received surgery (HR, 0.55; 95% CI, 0.40-0.76).

The specific amount of chemotherapy received was an important factor in the risk reduction.

“The risk of a second testicular cancer decreased with each additional cisplatin-based chemotherapy cycle administered,” Ragnhild Hellesnes, MD, department of oncology, University Hospital of North Norway, said when presenting that findings during the 2020 ESMO Virtual Congress. She also noted that the risk of developing a second testicular cancer was higher in younger patients.

Providing background for the study, Hellesnes said, “After being diagnosed with a primary germ cell testicular cancer, the risk of developing a second germ cell tumor in the contralateral testicle is increased with an estimated 15- to 20-year cumulative incidence of 1.9% to 3.9%.”

It has been hypothesized that cisplatin-based chemotherapy lowers the incidence of a metachronous contralateral (second) cancer, but there is no definitive data in the literature that supports this hypothesis. Thus, Hellesnes et al sought to assess the risk of developing a second cancer in this patient population, with a focus on prior treatment with cisplatin-based chemotherapy.

The researchers evaluated patient data from the Cancer Registry of Norway. The cohort they assessed included 5620 men diagnosed with a first unilateral testicular cancer between 1980 and 2009. Using patients medical records, the investigators were able to access complete treatment details for each patient.

“We estimated cumulative incidence of second testicular cancer, and to compare the risk to the general population, we calculated standardized incidence ratios. The effect of treatment intensity on the second testicular cancer risk was investigated using Cox regression,” said Hellesnes.

The median follow-up time for the total study population was 18 years. After a median of 6.2 years (interquartile range, 3.3-10.6), 218 men were diagnosed with a second testicular cancer.

Across the overall study cohort, the 20-year crude cumulative incidence of a second testicular cancer was 4%, which the researchers determined was 13.1-fold higher than the risk of developing testicular cancer in the general population. Among patients aged ≥30 at diagnosis, the risk of developing a second testicular cancer was 2.8% compared with 6% in patients who were aged <30 years at diagnosis.

Hazard ratios showed that the risk of developing a second cancer decreased with each additional chemotherapy cycle: 1 cycle (HR, 1.01); 2 cycles (HR, 0.74); 3 cycles (HR, 0.53); 4 cycles (HR, 0.41); >4 cycles (HR, 0.21). The risk reductions were statistically significant after ≥3 cycles.

The American Cancer Society estimates that in 2020, there will be approximately 9610 new cases of testicular cancer diagnosed, with approximately 440 individuals dying of testicular cancer.²

References

1. Hellesnes R, Myklebust TÅ, Kvammen Ø, et al. Metachronous contralateral testicular cancer in the cisplatin era: A population-based cohort study. Ann Oncol. 2020;31(4). Abstract: 708MO.

2. Key Statistics for Testicular Cancer. American Cancer Society. Last revised January 8, 2020. Accessed October 7, 2020. https://bit.ly/2F8dFDI.