Hormone therapy during or after radiation therapy increases the risk of cardiovascular events

This study examined the effect of androgen deprivation therapy (ADT) on the risk of cardiovascular events (such as stroke or heart attack) in men treated with radiation therapy. Researchers concluded that ADT use during or after radiation therapy increases the risk of cardiovascular events.

Radiation therapy is a first-line treatment for localized (confined) prostate cancer. In cases of locally advanced prostate cancer (tumor protruding into nearby tissue), the risk of disease progression is high. Therefore, aggressive treatment is needed early on. This often involves a combination of radiation therapy and ADT.

ADT targets the production of male sex hormones (such as testosterone) and reduces their effect on cancer cell growth. In some patients, ADT can cause side effects such as high blood pressure, weight gain, high blood glucose, and high cholesterol levels. These are associated with an increased risk of cardiovascular events (such as stroke or heart attack). Addressing the risk of cardiovascular events is particularly important for men undergoing long-term ADT.

This study aimed to examine the risk of cardiovascular events (CEs) in men treated with radiation therapy and ADT.

The records of 2,211 men treated with radiation therapy for localized prostate cancer were analyzed. 44.8% of men received ADT at the time of radiation therapy for an average of 6.1 months. 26.1% of men were classified as having high-risk prostate cancer. The incidences of CEs were followed for an average of 9.3 years.

16.5% of men received ADT after radiation therapy due to disease recurrence or progression (salvage ADT). Salvage ADT was started on average 5.5 years after radiation therapy and continued for an average of 4.3 years.

355 men (16.1%) experienced 431 CEs during the study period. The average time from radiation therapy to first CE was 5.6 years. The 10-year incidence of CEs after radiation therapy was 19.6% among men receiving ADT at the time of radiation therapy. This was significantly greater compared to men treated with radiation therapy alone (14.3%). Overall, ADT during radiation therapy increased the risk of CEs by 34%. Salvage ADT increased the risk of CEs by 77%.

Older age (68 years or older) increased CE risk by 29%. Higher rates of smoking increased the risk of CEs by 42%. The risk of experiencing a CE was increased by 69% for men with a diagnosis of diabetes. CE risk increased 2.15-fold for men with a history of a CE before starting radiation therapy.

A model using patient age, smoking status, history of CE before radiation therapy, diabetes, as well as ADT use at the time of radiation therapy predicted the rate of CEs at 10 years with an accuracy of 81%.

Researchers concluded that ADT use during or after radiation therapy increases the risk of cardiovascular events. Researchers advised that patients considering ADT should be screened for cardiovascular risk.