Cancer is one of the leading causes of death around the world. Every year, millions of people are diagnosed with different forms of the disease.
Over the past several decades, major advances in medicine have improved cancer treatments and helped many patients live longer. However, scientists are still trying to understand why the disease and its treatments affect people differently.
A new international study led by researchers at the University of Adelaide has uncovered an important difference between men and women when it comes to cancer outcomes.
The research shows that women with cancer are more likely to survive than men, but they are also more likely to experience serious side effects from cancer treatment. The findings were published in the JNCI: Journal of the National Cancer Institute.
The research team analyzed data from more than 20,000 cancer patients who participated in 39 large clinical trials. These trials were conducted between 2011 and 2021 and helped support drug approvals by the U.S. Food and Drug Administration.
The patients included in the study had 12 different types of advanced solid tumors. These cancers included lung cancer, colorectal cancer, melanoma, breast cancer, and several other major forms of the disease.
By examining such a large group of patients, the researchers were able to look for patterns that might not appear in smaller studies. Instead of focusing on how a single treatment works for men or women, the team asked a broader question.
They wanted to know whether biological sex itself could predict how patients respond to cancer and its treatments, regardless of which drugs were used.
The results showed a clear pattern. Female cancer patients had a 21 percent lower risk of death compared with male patients. In other words, women were more likely to survive their cancer than men across many different types of tumors and treatments.
However, the study also revealed another important finding. Women had a 12 percent higher risk of experiencing severe or harmful side effects from cancer treatment. These toxic side effects can include extreme fatigue, organ damage, immune reactions, and other complications that may require hospitalization or adjustments to treatment.
Lead author Dr. Natansh Modi explained that these results highlight the powerful role biological sex plays in how the body responds to disease and medication. According to him, sex influences many basic processes in the body, including how the immune system works, how drugs are processed, body composition, and even how tumors grow and behave.
Despite this knowledge, sex differences are often overlooked in medical research. In many clinical trials, results for men and women are combined rather than analyzed separately. As a result, doctors may not always have clear information about how treatments affect male and female patients differently.
Dr. Modi said this study helps address that problem by examining survival and side effects across many cancers and treatment types. The fact that the same pattern appeared across different therapies—including chemotherapy, targeted treatments, and immunotherapy—suggests that the differences are driven by underlying biology rather than a specific drug.
The findings may have important implications for how doctors treat cancer in the future. If women are more likely to experience serious side effects, doctors may need to monitor them more closely or adjust doses to reduce harmful reactions. At the same time, researchers want to understand why men appear to have worse survival outcomes.
Scientists believe several biological factors could explain these differences. Hormones such as estrogen and testosterone may influence how cancer grows or how the immune system responds to tumors.
Differences in body fat, muscle mass, and metabolism can also change how drugs move through the body. In addition, men and women may process medications at different speeds, which can affect both effectiveness and toxicity.
The study’s authors say more research is needed to fully understand these biological mechanisms. Future studies may examine how hormone levels, immune responses, and drug exposure interact with cancer treatments in men and women.
Understanding these differences could help doctors design more personalized treatment strategies. Personalized medicine aims to tailor medical care to each patient’s unique characteristics, including genetics, lifestyle, and biological sex. Recognizing sex as an important factor could improve both survival rates and quality of life for cancer patients.
The researchers also believe their findings highlight the need for changes in how clinical trials are designed and reported. They recommend that sex should be treated as a core factor in cancer research, rather than an afterthought. Reporting results separately for men and women could provide valuable information for doctors and patients making treatment decisions.
Overall, the study provides strong evidence that biological sex plays an important role in cancer outcomes. Women appear to have a survival advantage across many types of cancer, but this benefit often comes with a higher risk of serious treatment-related side effects.
These findings should not be interpreted to mean that one sex is simply “better off” than the other. Instead, they show that cancer affects men and women differently and that treatment strategies may need to be adjusted to reflect those differences.
One strength of the study is its very large dataset, which included more than twenty thousand patients across many types of cancer and treatment approaches. This broad analysis strengthens confidence that the patterns observed are real and not limited to a single cancer type.
However, the study also has limitations. Because the analysis relied on previously completed clinical trials, it could not fully explain the biological reasons behind the differences. More detailed biological research will be needed to understand the mechanisms that drive these patterns.
Even with these limitations, the findings offer an important message for modern cancer care. Recognizing and studying sex differences may help improve survival while reducing harmful side effects for both men and women.
If you care about cancer, please read studies that artificial sweeteners are linked to higher cancer risk, and how drinking milk affects risks of heart disease and cancer.
For more health information, please see recent studies about the best time to take vitamins to prevent heart disease, and results showing vitamin D supplements strongly reduces cancer death.
The study was published in the JNCI: Journal of the National Cancer Institute.
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