Does sex matter in colon cancer screening?
Middle-aged men are twice as likely as women to end up with a cancer diagnosis after colonoscopy, according to an Austrian study that challenges screening guidelines.
Guidelines currently advise that people at average risk of colon cancer start screening for the disease at age 50, regardless of gender.
But the new work, published in the Journal of the American Medical Association, shows a discrepancy of nearly 10 years between men and women in the development of colon and rectal tumors.
That means the same number of 55-year-old men would need to undergo colonoscopies - in this case, around 80 - to spot one cancer, as would be true for 65-year-old women. The same logic held true for the pre-cancerous growths called advanced adenomas, which doctors also scout for during colonoscopies.
However, a U.S. expert warned about making decisions regarding when to start screening based on the new findings.
“I would discourage women from looking at this study and saying, ‘Gee, I can wait longer,’” said Dr. Michael LeFevre of the U.S. Preventive Services Task Force, a federally supported expert panel. “And I would discourage men from saying, ‘Gee, I should start sooner.’”
Sex, Age And Ethnicity Assciated With Colorectal Cancer Survival
The interaction of sex, age and ethnicity has a significant impact on overall survival in metastatic colorectal cancer (MCRC) patients, a study led by researchers at the University of Southern California (USC) and USC/Norris Comprehensive Cancer Center suggests.
While age and ethnicity are well-established factors that impact survival in colorectal cancer, the study found that gender also plays an important role in overall survival, says Andrew Hendifar, M.D., MPH, fellow in the division of hematology/oncology at the Keck School of Medicine of USC and lead author of the study. Researchers found that pre-menopausal women with metastatic colorectal cancer (18-44 years old) lived longer than younger men, while older women (75 and older) had significantly worse overall survival than older men.
The study adds to the growing evidence that female hormones are protective for colon cancer, researchers say.
“This study provides further evidence that estrogen may play an important role not only in colon cancer development but also progression of the disease, and may impact how we develop therapies for women and men with colon cancer,” says Heinz-Josef Lenz, M.D., professor of medicine at the Keck School of Medicine and a senior investigator on the study.
Researchers screened 56,598 patients with metastatic colorectal cancer from 1988 to 2003, using the Surveillance, Epidemiology and End Results (SEER) registry. Models were created using the patients’ age at diagnosis, sex, ethnicity and overall survival. Independent of age, there were no survival differences between men and women with MCRC. However, when age was added to the model, sex became significantly associated with survival across all ethnicities.
Researchers also found that certain ethnicities had better overall survival than others. Namely, Hispanics and Asians have better outcomes than Caucasians and African-Americans. Further studies in this area should look at how certain diets or specific surroundings contribute to the development of colorectal cancer, Hendifar notes.
The USPSTF recommends colon cancer screening between the ages of 50 and 75 using one of a number of types of tests. The advantage of colonoscopy, which costs around $3,000, is that it only has to be repeated once every ten years, as opposed to every year for the much cheaper stool test.
About one in 19 men develops colon cancer at some point and slightly fewer women do. The disease, which usually strikes older adults, is the third leading cause of cancer deaths in the U.S.
To get a better idea of when to start screening, Dr. Monika Ferlitsch and her colleagues looked at data from more than 44,000 Austrians, who’d had colonoscopies between 2007 and 2010.
Overall, they found 25 percent of men had adenomas, compared to only 15 percent of women. For full-blown tumors, those numbers were 1.5 percent and 0.7 percent, respectively.
At 0.8 percent, the rate of colon cancer among men aged 50 to 54, for instance, was twice that found among women in the same age group. That means 125 men would need to have a colonoscopy to find one tumor, versus 264 women.
While the reasons for the difference are still murky, Ferlitsch, of the Medical University of Vienna, said it could be linked to a higher degree of overweight and fatty liver disease among men - both of which have been linked to colon cancer.
While her team suggests “screening recommendations concerning age should be reconsidered,” Ferlitsch wasn’t ready to give practical advice.
Age and sex differences in right colon cancer
In a prospective study of 402 colorectal cancer patients, 133 patients (46 men and 87 women) presented with right colon cancer. There was no significant difference between men and women in right colon cancer incidence. Common presenting features were abdominal pain, weight loss, and anemia. Ninety-one patients underwent resection with curative intent. There were significantly fewer Dukes’ A tumors in the right colon cancer series (P less than 0.05). Significantly more women in the right colon cancer group were over 70 years old (P less than 0.05). The findings of peritoneal metastases and poorly differentiated lesions at initial surgery also were associated significantly with women who had right colon cancer (P less than 0.05). This study confirms previous reports of more advanced tumors in the right colon. The need for age, sex, and subsite differences to be taken into account when assessing treatment outcomes or survival is emphasized.
###
Alley PG, McNee RK.
“It’s a difficult question if we should delay screening in women or start it earlier in men,” she told Reuters Health.
LeFevre said the USPSTF will take the new results into consideration as the panel updates its guidelines over the next couple of years.
Meanwhile, he told Reuters Health, “I think people can safely stick with the recommendation on the table to start screening at age 50, whether they are a man or a woman.”
SOURCE: Journal of the American Medical Association, September 27, 2011.