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Understanding Sex Differences in Cancer Risk and Survival

Understanding Sex Differences in Cancer Risk and Survival

Though both men and women can develop cancer due to a variety of risk factors. There are some factors related to gender that affect both risk and outcome of treatment. What exactly are the gender or sex differences in cancer risk and survival?

To better understand this, it helps to look at they types of cancer common in both sexes.

In men, the most prevalent forms of cancer are prostate, colorectal, and lung cancers, which is estimated to be 43% of all cancers diagnosed in men.

Women on the other hand, more commonly develop lung, breast, and colorectal cancer, encompassing half of all new cancers diagnosed in women.

The age standardized rate for all cancers globally as of 2018 is 197.9 per 100,000 people, this includes non-melanoma skin cancers (Squamous cell carcinomas and Basal cell carcinomas) and is a combined metric for both men and women.

However, men are more likely to develop cancer than women (218.6 per 100,000 men compared to 182.6 per 100,000 women).

Sex Differences in Cancer Risk and Survival: Prevalence of cancer types

Previous data has shown that men are 20% more likely to develop cancer than women. They are also 40% more likely to die from cancer than women.

To understand why this is so, we must discuss the genetic/molecular differences between men and women.

Aside from cancer that affect sex-specific organs, sex differences can be seen in trends of other types of cancer.

This includes, but is not limited to:

  • Cancers with a higher incidence in women
    • Thyroid
  • Cancers with a higher incidence in men
    • Colorectal
    • Stomach cancer
    • Liver cancer
    • Bladder cancer
    • Leukemia

sex differences in cancer risk and survival

How sex or gender influences cancer mortality

When it comes to sex differences in cancer risk and survival, it’s important to know that men are more likely to die due to cancer.

This is most evident when comparing the mortality rate of colorectal, lung, and stomach cancers between men and women.

However, it should be noted that women with cancers of the breast, uterus, and ovaries show a high mortality rate as well.

With the information available to us, the trends show that men are more likely to develop and subsequently die due to cancer.

This can be attributed to the lifestyle and behavior that is associated with most men.

Lung cancer, for example, is the leading cause of cancer death in men, mostly due to smoking.

Genetic/molecular differences in men and women

The genetic/molecular basis for the sex difference in the development and severity of cancers can be linked to genetic polymorphism.

This means genetic variation seen in different individuals.

Hormonal differences in men and women

Sex hormones also play a significant role in the development of cancer. As mentioned previously, high levels and long-term exposure of women to estrogen is a known risk factor in the development of breast cancer.

In contrast, estrogen exposure in men is limited. So their lower risk of developing breast cancer is evident in current statistics. Estrogen is also linked to a higher incidence of thyroid cancer among women.

Reaction to therapy

In the treatment of cancer, chemotherapeutic drugs may be metabolized differently by men and women.

The clearance of some drugs may differ, causing a potentially dangerous drug to stay in the body for longer than other drugs. This may cause drug toxicity which causes adverse effects/ side effects.

For example, patients taking the chemotherapeutic drug 5-fluorouracil, a drug used in the treatment of colon, rectal, stomach, and pancreatic cancers, may causes adverse effects in women, such as stomatitis, leukopenia (decreased number of white blood cells), alopecia (balding), and diarrhea.

This is due to a poorer clearance of this drug, when taken by women compared to men.

This trend is seen in several chemotherapeutic agents, such as your paclitaxel, cisplatin, doxorubicin, rituximab, and bevacizumab, which can complicate treatment due to the increased incidence of adverse effects in women. Although this plays a role in the outcome of patient treatment, it does not completely determine the outcome of cancer.

In fact, early diagnosis of cancer is a more significant determinant of cancer outcomes, as this would permit treatment of cancer in its earlier stages, increasing the chance of curative therapy.

Some recent studies do state that immunotherapy in the treatment of cancer shows a sex-linked variance in its outcomes.

Men were noted to respond better to therapies that repress the immune system and that women respond more to immune therapies that stimulate immunity. However, evidence is limited and requires further investigation.

Key Takeaways

When it comes to sex differences in cancer risk and survival, there are multiple factors at work. These can be due to genetic or molecular variance through genetic polymorphism and the influence of estrogen in the development and protection from certain types of cancer.

Men are generally more susceptible to the development of cancer, however, some cancers such as thyroid cancer is more commonly seen in women. Therapy outcomes typically favor men, since women experience more adverse effects throughout the course of treatment.

New therapeutic regimens in the treatment of cancer, specifically immunotherapy show some variance in treatment for men and women. Proper screening and early diagnosis is still the best indicator of good outcomes for both men and women who are at risk.

Learn more about cancer causes and risk factors, here.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Global Cancer Data per Country https://www.wcrf.org/dietandcancer/cancer-trends/data-cancer-frequency-country Accessed December 30, 2020

Worldwide Cancer Data https://www.wcrf.org/dietandcancer/cancer-trends/worldwide-cancer-data Accessed December 30, 2020

Cancer Statistics https://www.cancer.gov/about-cancer/understanding/statistics Accessed December 30, 2020

Breast Cancer Risk Factors https://www.breastcancer.org/symptoms/understand_bc/risk/factors Accessed December 30, 2020

Sex Differences in Cancer: Epidemiology, Genetics and Therapy

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6029678/ Accessed December 30, 2020

UniProtKB – P50225 (ST1A1_HUMAN)

https://www.uniprot.org/uniprot/P50225 Accessed December 30, 2020

5-fluorouracil

https://www.cancer.gov/publications/dictionaries/cancer-terms/def/5-fluorouracil Accessed December 30, 2020

Promoting Cancer Early Diagnosis https://www.who.int/cancer/prevention/diagnosis-screening/en/ Accessed December 30, 2020

The impact of sex and gender on immunotherapy outcomes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7197158/

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Medical reviewed by Dr. John Paul Abrina, M.D.
Written by Ruby Anne Hornillos
Updated Dec 30, 2020
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