Women are more likely to survive cancer than men, but they’re also more likely to develop severe side effects to treatment, a new evidence review says.

Female cancer patients have a 21% lower risk of death than men across 12 different types of advanced cancers, researchers recently reported in the Journal of the National Cancer Institute.

However, they have a 12% higher risk of adverse effects from the chemotherapy, radiation therapy and other treatments used to save their lives, researchers found.

“Women demonstrated a survival advantage, but at the cost of increased severe toxicity,” lead researcher Natansh Modi, a lecturer in pharmacology at Adelaide University in Australia, said in a news release.

For the new study, researchers analyzed data from more than 20,000 cancer patients across 39 trials that supported U.S. drug approvals between 2011 and 2021. 

The trials spanned 12 advanced types of solid tumors, including lung, colon, melanoma and breast cancers.

The results provide clear evidence that sex is a key predictor of outcomes in cancer treatment, Modi said.

“Sex is a fundamental biological factor that influences immune function, drug metabolism, body composition and tumor biology,” Modi said. “Yet despite longstanding recommendations from regulatory and funding bodies to report outcomes by sex, it is still treated as an afterthought in many trials and is rarely factored into baseline risk or used to personalize treatment decisions.”

Making sex a consideration in deciding cancer care could have powerful implications for how cancer drugs are developed and prescribed, researchers said.

“This is about improving outcomes for every cancer patient,” Modi said. “If women are living longer but experiencing more severe side effects, we need to acknowledge that and respond to it. At the same time, we need to better understand why male patients appear to have poorer survival.”