More than 1 in 10 Americans over age 60 years will be diagnosed with cancer, according to the National Cancer Institute, making screening for the disease in older patients imperative. Much of the burden of cancer screening falls on primary care physicians. This news organization spoke recently with William L. Dahut, MD, chief scientific officer of the American Cancer Society, about the particular challenges of screening in older patients.
Question: How much does cancer screening change with age? What are the considerations for clinicians – what risks and comorbidities are important to consider in older populations?
Answer: We at the American Cancer Society are giving a lot of thought to how to help primary care practices keep up with screening, particularly with respect to guidelines, but also best practices where judgment is required, such as cancer screening in their older patients.
We've had a lot of conversations recently about cancer risk in the young, largely because data show rates are going up for colorectal and breast cancer in this population. But it's not one size fits all. Screening for young women who have a BRCA gene, if they have dense breasts, or if they have a strong family history of breast cancer should be different from those who are at average risk of the disease.
But statistically, there are about 15 per 100,000 breast cancer diagnoses in women under the age of 40 while over the age of 65 it's 443 per 100,000. So, the risk significantly increases with age but we should not have an arbitrary cut-off. The life expectancy of a woman at age 75 is about 13.5 years. If you're over the age of 70 or 75, then it's going to be comorbidities that you look at, as well as individual patient decisions. Patients may say, "I don't want to ever go through a mammogram again, because I don't want to have a biopsy again, and I'm not going to get treated." Or they may say, "My mom died of metastatic breast cancer when she was 82 and I want to know."
Q: How should primary care physicians interpret conflicting guidance from the major medical groups? For example, the American College of Gastroenterology and your own organization recommend colorectal cancer screening start at age 45 now. But the American College of Physicians recently came out and said 50. What is a well-meaning primary care physician supposed to do?
A: We make more of guideline differences than we should. Sometimes guideline differences aren't a reflection of different judgments, but rather what data were available when the most recent update took place. For colorectal cancer screening, the ACS dropped the age to begin screening to 45 in 2018 based on a very careful consideration of disease burden data and within several years most other guideline developers reached the same conclusion.
However, I think it's good for family practice and internal medicine doctors to know that significant GI symptoms in a young patient could be colorectal cancer. It's not as if nobody sees a 34-year-old or 27-year-old with colorectal cancer. They should be aware that if something goes away in a day or two, that's fine, but persistent GI symptoms need a cancer workup – colonoscopy or referral to a gastroenterologist. So that's why I think age 45 is the time when folks should begin screening.
Q: What are the medical-legal issues for a physician who is trying to follow guideline-based care when there are different guidelines?
A: Any physician can say, "We follow the guidelines of this particular organization." I don't think anyone can say that an organization's guidelines are malpractice. For individual physicians, following a set of office-based guidelines will hopefully keep them out of legal difficulty.
Q: What are the risks of overscreening, especially in breast cancer where false positives may result in invasive testing?
A: What people think of as overscreening takes a number of different forms. What one guideline would imply is overscreening is recommended screening by another guideline. I think we would all agree that in an average-risk population, beginning screening before it is recommended would be overscreening, and continuing screening when a patient has life-limiting comorbidities would constitute overscreening. Screening too frequently can constitute overscreening.
For example, many women report that their doctors still are advising a baseline mammogram at age 35. Most guideline-developing organizations would regard this as overscreening in an average-risk population.
I think we are also getting better, certainly in prostate cancer, about knowing who needs to be treated and not treated. There are a lot of cancers that would have been treated 20-30 years ago but now are being safely followed with PSA and MRI. We may be able to get to that point with breast cancer over time, too.
Q: Are you saying that there may be breast cancers for which active surveillance is appropriate? Is that already the case?
A: We're not there yet. I think some of the DCIS breast cancers are part of the discussion on whether hormonal treatment or surgeries are done. I think people do have those discussions in the context of morbidity and life expectancy. Over time, we're likely to have more cancers for which we won't need surgical treatments.
Q: Why did the American Cancer Society change the upper limit for lung cancer screening from 75 to 80 years of age?
A: For an individual older than 65, screening will now continue until the patient is 80, assuming the patient is in good health. According to the previous guideline, if a patient was 65 and more than 15 years beyond smoking cessation, then screening would end. This is exactly the time when we see lung cancers increase in the population and so a curable lung cancer would not previously have been detected by a screening CT scan. *
Q: What role do the multicancer blood and DNA tests play in screening now?
A: As you know, the Exact Sciences Cologuard test is already included in major guidelines for colorectal cancer screening and covered by insurance. Our philosophy on multicancer early detection tests is that we're supportive of Medicare reimbursement when two things occur: 1. When we know there's clinical benefit, and 2. When the test has been approved by the FDA.
The multicancer early detection tests in development and undergoing prospective research would not now replace screening for the cancers with established screening programs, but if they are shown to have clinical utility for the cancers in their panel, we would be able to reduce deaths from cancers that mostly are diagnosed at late stages and have poor prognoses.
There's going to be a need for expertise in primary care practices to help interpret the tests. These are new questions, which are well beyond what even the typical oncologist is trained in, much less primary care physicians. We and other organizations are working on providing those answers.
Q: While we're on the subject of the future, how do you envision AI helping or hindering cancer screening specifically in primary care?
A: I think AI is going to help things for a couple of reasons. The ability of AI is to get through data quickly and get you information that's personalized and useful. If AI tools could let a patient know their individual risk of a cancer in the near and long term, that would help the primary care doctor screen in an individualized way. I think AI is going to be able to improve both diagnostic radiology and pathology, and could make a very big difference in settings outside of large cancer centers that operate at high volume every day. The data look very promising for AI to contribute to risk estimation by operating like a second reader in imaging and pathology.
Q: Anything else you'd like to say on this subject that clinicians should know?
A: The questions about whether or not patients should be screened is being pushed on family practice doctors and internists and these questions require a relationship with the patient. A hard stopping point at age 70 when lots of people will live 20 years or more doesn't make sense.
There's very little data from randomized clinical trials of screening people over the age of 70. We know that cancer risk does obviously increase with age, particularly prostate and breast cancer. And these are the cancers that are going to be the most common in your practices. If someone has a known mutation, I think you're going to look differently at screening them. And first-degree family members, particularly for the more aggressive cancers, should be considered for screening.
My philosophy on cancer screening in the elderly is that I think the guidelines are guidelines. If patients have very limited life expectancy, then they shouldn't be screened. There are calculators that estimate life expectancy in the context of current age and current health status, and these can be useful for decision making and counseling. Patients never think their life expectancy is shorter than 10 years. If their life expectancy is longer than 10 years, then I think, all things being equal, they should continue screening, but the question of ongoing screening needs to be periodically revisited.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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Cite this: Q&A: Cancer Screening in Older Patients – Who to Screen and When to Stop - Medscape - Nov 03, 2023.
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