(Reuters Health) – Colorectal cancer screening with colonoscopy or sigmoidoscopy in healthy seniors over age 75 may reduce cancer incidence and death, a new study suggests.
An analysis of data from more than 56,000 health professionals followed for decades found that, overall, screening adults over 75 was associated with a 39% reduction in the incidence of colorectal cancers and a 40% drop in the risk of colorectal cancer death. In seniors who had not been screened prior to age 75, screening after age 75 was associated with a 49% reduction in cancer incidence and 37% reduction in colorectal cancer mortality, according to the results published in JAMA Oncology.
“Until now, it’s been really unclear whether there is a continued benefit to screening people for colorectal cancer after age 75,” said study coauthor Dr. Andrew Chan, a professor of medicine at the Harvard Medical School and a gastroenterologist at Massachusetts General Hospital in Boston. “There’s really been a lack of data to support or refute a benefit. So it’s been difficult for clinicians to feel comfortable making recommendations. This study provides strong evidence for screening after age 75 for many, particularly those who do not have cardiovascular risk factors.”
The new study focused on lower gastrointestinal screening endoscopy as the screening method, Dr. Chan said. “During the period of time we studied this was the default mode of screening,” he added. “There has been increasing interest and support in other screening modalities, including noninvasive stool-based tests, which could potentially further tilt the risk-benefit equation to doing more screening in older populations.”
To take a closer look at the potential benefits of screening older seniors, Dr. Chan and his colleagues turned to data from the Nurses’ Health Study (NHS), which included 121,701 female registered nurses aged 30 to 55 years at enrollment in 1976, and the Health Professionals Follow-up Study (HPFS), which included 51,529 male clinicians aged 40 to 75 years at enrollment in 1986.
In both the NHS and the HPFS, beginning in 1988 and continuing through 2014, participants were asked as part of biennial questionnaires whether they had undergone either sigmoidoscopy or colonoscopy in the past two years and, if so, the reason for the investigation.
The current analysis focused on 56,374 seniors who reached age 75 during follow-up (63.2% women), among whom there were 661 incident colorectal cancer cases and 323 colorectal-related deaths.
Screening endoscopy after age 75 was associated with a reduced risk of colorectal cancer incidence, (multivariable hazard ratio 0.61) and colorectal cancer-related mortality (HR 0.60), regardless of screening history. Comparing screening versus non-screening in those older than 75 yielded reduced risk for colorectal cancer incidence (HR 0.67) and for colorectal cancer-related mortality (HR 0.58) among those who underwent screening endoscopy before 75 years of age, as well as colorectal cancer incidence (HR 0.51) and colorectal cancer-related mortality (0.63) among participants without a screening history.
Screening endoscopy after 75 years of age was not associated with risk reduction in colorectal cancer-related death among participants with cardiovascular disease (HR 1.18) or those who had three or more comorbidities (HR 1.17), such as cardiovascular disease (myocardial infarction or stroke), hypertension, hypercholesterolemia, and diabetes.
The results of the new study may not apply to the average American, said Dr. Otis Brawley, a professor of oncology and epidemiology at the Johns Hopkins School of Medicine and the Johns Hopkins Bloomberg School of Public Health in Baltimore.
The study suggests a benefit to screening with endoscopy in those over 75, but the problem is that it is based on the Nurses’ Health Study and the Health Professionals Follow-up Study, Dr. Brawley said. “When you look at studies like this you have to remember the ‘healthy volunteer effect,’ because the participants are generally healthier than people of the same age,” he added.
The most recent set of guidelines from the U.S. Preventive Services Task Force, issued in May of 2021, recommended “that clinicians selectively offer screening for colorectal cancer in adults aged 76 to 85 years. Evidence indicates that the net benefit of screening all persons in this age group is small. In determining whether this service is appropriate in individual cases, patients and clinicians should consider the patient’s overall health, prior screening history, and preferences.”
Putting those recommendations into practice may be difficult for most clinicians, Dr. Brawley said.
“It’s difficult for a doctor to look a patient in the eye and say we’re not going to screen you for colorectal cancer because you don’t have a 10-year life expectancy,” Dr. Brawley said. “When I was with the American Cancer Society, we desperately tried not to put maximum ages for screening because if a patient is in reasonably good health it does not make sense to stop screening.”
Nevertheless, other, less invasive screening modalities might be a better choice for older patients because the risk of complications in seniors is higher, Dr. Brawley said. “There was a study that found that in one out of every 600 Medicare beneficiaries who got screening colonoscopy, Medicare ended up paying for treatment for perforations,” he added.
SOURCE: https://bit.ly/3vk5id1 and https://bit.ly/3uibfpM JAMA Oncology, online May 20, 2021.
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