March is Colon Cancer Awareness month, a public health outreach effort to reduce the devastating toll of the number two cancer killer in the U.S. With over 150,000 new cases and 52,000 deaths each year, colon cancer impacts men and women and is now taking the lives of younger adults more than ever before.

Unfortunately, women perceive Colorectal Cancer (CRC) as a predominantly male disease with less consequence for themselves. The actual lifetime risk is 1 in 23 for men and 1 in 26 for women. As they often delay seeking care, 27.6 percent of CRC cases for women can present with more advanced disease compared to 22.1 percent for men, resulting in higher morbidity and mortality.

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While they are more aware of the high value of screening programs, women participate less than their male counterparts as they express greater concern about discomfort and embarrassment to their health care providers. Women are also more likely to find colonoscopy preparation a barrier, resulting in lower participation in screening programs. While CRC is somewhat more common in males, it is the female who is more likely to have a delayed diagnosis, with polyps that are more difficult to discover than those that develop in men.

Gender Differences in Colorectal Cancer

Sexual dimorphism is obvious from external appearances, but even shared internal anatomy, such as the colon, has distinct gender differences. The gender differences in colorectal cancer are well recognized in the medical community and yet have not been incorporated into clinical care guidelines for screening and surveillance.

Even though women typically have a smaller stature than men, the female colon is actually longer and narrower than the male colon and has more convolutions and tortuosity. The increased length and challenging anatomy make the proximal colon more difficult to reach and fully inspect during a colonoscopy. Colonoscopies for women are more technically challenging, have a longer procedure time, a higher rate of missed polyps and cancers, and a higher complication rate with increased morbidity and mortality. Women are also more likely to have a history of abdominal or pelvic surgery, increasing the risks of adhesions that may distort anatomy and raise the risk of complications from the mechanical manipulation and pressure of the colonoscope and colonic distention.

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These gender differences in CRC epidemiology, etiology, biology, and screening can impact diagnosis, and prognosis. Women are frequently told after a procedure that their colon was “tortuous” and therefore difficult to thoroughly evaluate.

Hormones Have an Impact

In both preclinical and clinical research, estrogen is recognized as having an effect on CRC. Dietary consumption of soy products, which contain bioactive phytoestrogens, has been shown to reduce the risk of CRC. As the use of oral contraceptives and hormone replacement therapy has increased, the protective effect of hormonal use may have had an influence on CRC risk for women.

The Women’s Health Initiative trial of estrogen plus progestin in postmenopausal women provided supporting evidence that the use of these hormones was associated with a 40 percent decrease in the risk of CRC.

Screening Recommendations

We must change the narrative on screening recommendations to consider gender differences. Females at average risk of CRC have less benefit and greater risk with the colonoscopy procedure, resulting in missed polyps, especially sessile serrated adenomas, missed and interval cancers, and higher incidence of incomplete examination and complications than males.

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Females may be better served by undergoing screening with a non-invasive or minimally invasive modality, such as a fecal immunochemical test (FIT), multitarget stool DNA, or CT colonography. Even those in a high-risk category (e.g. past history of colon polyp, family history of CRC, etc.) may consider a noninvasive approach as a preliminary step. You can proceed to colonoscopy if the noninvasive test has a positive result.

The optimal approach for prevention, screening, diagnosis, and therapy, should be tailored to each individual, and gender is an important aspect that historically has not been given due consideration.

Over one-third of the at-risk U.S. population does not participate in CRC screening. Colonoscopy is an important and valuable diagnostic and therapeutic tool, but the disadvantages are significant. They include high cancer and polyp miss rates, high discomfort, challenging and frequently inadequate preparation, and high operator quality variability.

Screening recommendations do not take gender differences into account. The lack of gender specificity in screening tools may partially explain the higher mortality rate of women.

Universal CRC screening can save lives, health, and wealth. While colonoscopy is the leading CRC screening and surveillance examination in the United States, it has been overpromoted and overutilized. It has the advantage of allowing polypectomy and biopsy during an examination but is offset by higher rates of morbidity, mortality, and expense.

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The dictum of Hippocrates, “primum non nocere (above all do no harm),” requires that we reconsider how we promote procedures and services, especially when the vast majority of screening subjects are healthy and will have negative results. Evidence-based research and common sense support the consideration of noninvasive studies rather than invasive colonoscopy for CRC screening in the average risk population, especially women.

In recent years, in response to calls for more equitable health care provision, gastroenterologist have collectively issued the following statement: “As health care providers, we have dedicated our lives to caring for our fellow human beings. Therefore, we are compelled to speak out against any treatment that results in unacceptable disparities that marginalize the vulnerable among us.” As the gastroenterology societies in the United States are sister organizations, it would be appropriate that this commitment be extended to protecting the well-being of the female population. A re-examination of the risks and benefits of CRC screening, especially regarding the heavy promotion of invasive colonoscopy is overdue.