The risk of different types of second cancers in prostate cancer survivors

This study examined the risk of different types of second cancers in prostate cancer survivors. Researchers reported a reduced risk of various second cancers among men with prostate cancer compared to the cancer incidence in the general population.

Advances in treatment and early detection of prostate cancer have increased survival and led to a growing number of men living with prostate cancer. The increased life expectancy of prostate cancer survivors exposes them to the possibility of later developing second cancers. Previous studies have estimated that about 16% of prostate cancer survivors are later affected by second cancers. How the risk of different types of second cancers compares to the general population has not been fully studied.

The aim of this study was to compare the risk of second cancers in men with prostate cancer, relative to the general population.

The records of 441,504 men with prostate cancer were analyzed. Prostate cancer was the first cancer diagnosis in all men included. Most men were aged between 65 and 74 years at the time of prostate cancer diagnosis. The incidence of second cancers was compared to the cancer rate of the general population. The diagnosis of a second cancer must have occurred at least 2 months after the prostate cancer diagnosis.

10% of men with prostate cancer later developed a second cancer. Compared with cancer incidence in the general population, men with prostate cancer had a lower overall risk of second cancers (about 40% lower). The risk was significantly reduced for a number of different second cancers. These included leukemia, oral cancers (including mouth, nasal, and esophagus cancer), respiratory cancers (lung, bronchus, and larynx), as well as cancers of the stomach, colon, rectum, liver, gallbladder, and pancreas. The reduced risk of these cancers was less pronounced for men who previously received radiation for prostate cancer.

Significant increases in the risk of cancers of the soft tissue, heart, bladder, kidney, and of the endocrine (metabolism) system were observed among men with prostate cancer. In the 2 to 11 months after prostate cancer diagnosis, men with prostate cancer were at increased risk of lymphoma, as well as bladder, kidney, thyroid, and endocrine system cancers. This risk then significantly decreased from 120 months after diagnosis.

Men with early-onset prostate cancer had a higher risk for bladder and thyroid cancer compared to the general population and compared to men with late-onset prostate cancer. The risk of a second cancer of the stomach, colon, bladder, kidney, and of leukemia was higher for black men with prostate compared to caucasian men with prostate cancer.

Researchers concluded that men with prostate cancer had a lower risk for various second cancers compared to the cancer incidence in the general population, but at a higher risk for others. Previous radiation, age at diagnosis and ethnicity affected long-term risk of second cancers.