Colorectal cancer, which includes both colon and rectal cancers, is a significant public health challenge affecting millions worldwide. This disease begins with the uncontrolled growth of cells in the lining of the large intestine. Its impact and risk profile vary between sexes, making it important to understand the specific data related to women. Focusing on incidence rates, unique female risk factors, and screening recommendations provides a clearer picture for prevention and early detection in the female population.
Prevalence and Incidence Rates
For the year 2024, an estimated 71,270 women are expected to be diagnosed with colorectal cancer in the United States. The lifetime risk of a woman developing this cancer is approximately 1 in 25, making it the third most commonly diagnosed cancer for both men and women. The incidence rate for women during 2015-2019 was recorded at 31.2 per 100,000, which is lower than the rate for men, likely due to differences in lifestyle and hormonal factors.
Historically, colorectal cancer cases and deaths in older adults have been declining, with the death rate dropping by 60% in women age 55 and above since 1969. This positive trend is largely attributed to increased screening adherence in the older population. However, this progress masks a troubling shift in the age demographic of new diagnoses.
Incidence rates are rising in younger women, a trend observed since the mid-1990s. For adults under age 55, the incidence rate has been increasing by 1% to 2% each year. This shift has made colorectal cancer the second leading cause of cancer death in women under 50. Approximately one in five new diagnoses are now occurring in people under the age of 55.
Risk Factors Specific to Women
A woman’s risk profile is uniquely influenced by hormonal fluctuations and specific reproductive health conditions. Hormonal factors are complex, as they can be both protective and detrimental depending on the type and timing of exposure. For example, the use of menopausal hormone therapy (HRT) combining estrogen and progestin has been associated with a significantly decreased risk of colorectal cancer.
This protective effect is linked to estrogen’s anti-inflammatory properties, which counteract the processes that lead to cancer development in the gut. Conversely, some studies suggest that a longer exposure to a woman’s own naturally higher levels of estrogen, indicated by a later age at menopause, may be associated with an increased risk in postmenopausal women who do not use HRT. The presence of greater visceral fat, the fat stored around internal organs, is also a disproportionate risk factor, as a higher waist-to-hip ratio is more strongly linked to increased colorectal cancer risk in women than in men.
Certain gynecological inflammatory conditions are also being investigated for association with colorectal cancer risk. Endometriosis, a condition where tissue similar to the uterine lining grows outside the uterus, is one such factor. This link is believed to be driven by the chronic inflammation and hormonal imbalances characteristic of the disorder. Similarly, Polycystic Ovary Syndrome (PCOS), which involves hormonal imbalances and insulin resistance, has been suggested to elevate the risk for colon cancer through mechanisms like chronic inflammation and obesity.
Screening Recommendations and Early Signs
Screening for colorectal cancer in women at average risk should begin at age 45, a recommendation updated from the previous age of 50 to address the rising incidence in younger adults. For average-risk women, a colonoscopy is recommended every 10 years. This is considered the gold standard because it allows for the removal of precancerous polyps during the procedure. Alternative screening options include stool-based tests, such as the highly sensitive Fecal Immunochemical Test (FIT) annually, or a multi-targeted stool DNA test every three years.
Recognizing early signs of the disease is paramount, especially since early-stage cancer is often asymptomatic. Symptoms such as a persistent change in bowel habits, rectal bleeding, unexplained weight loss, and chronic abdominal pain or cramping should prompt an evaluation. These symptoms, particularly in women, can be easily misattributed to common conditions like menstrual issues, Irritable Bowel Syndrome, or hemorrhoids.
A significant warning sign is unexplained iron-deficiency anemia, which causes persistent fatigue and shortness of breath. Symptoms that last longer than a typical menstrual cycle, or are accompanied by severe fatigue or blood in the stool, warrant immediate discussion with a healthcare provider. Timely screening and vigilance are the most effective tools for preventing disease progression.