By Dr. James A. Stewart, FACP for the Daily Hampshire Gazette, published April 5, 2016
Over the past years there has been a major shift in cancer screening guidelines with the fundamental objective of testing being to document the presence of a potentially significant cancer. There has been a shift in thinking on who and when a man should be tested for prostate cancer, as well as women for breast cancer. And, in the past year, new lung cancer screening has come to the forefront for heavy smokers.
Q: What is cancer screening and what value do doctors place on screening today?
A: The goal of cancer screening is to detect a cancer in its early stages, before signs and symptoms appear, hopefully before it has spread beyond a curable stage. The ultimate goal is to reduce death. Recent vigorous discussion and debate has resulted from greater attention being placed on the balance of benefit, harm, and value of cancer screening. Tests are done in large populations and are potentially very expensive to the overall health care system. For example, in the United States, screening mammography as implemented in recent decades, beginning with women at age 40, costs at least $7 billion a year. A successful screening program results in decreased deaths with no or minimal harm from the testing and follow-up process.
Q: What are the risks/harm involved in screening?
A: While screening tests can be beneficial in helping us to identify cancer at an earlier and more treatable stage, there are some downsides to testing. For example, screening can lead to overtreatment for some, when a test finds a cancer that may be so slow growing that it would not cause health problems to the patient in their lifetime. False positives can also lead to more invasive and expensive tests and overtreatment resulting in added costs. Screening and follow-up can cause anxiety for many patients. There are also possible physical harms to consider, such as the risk of perforating a patient’s colon during a screening colonoscopy.
The US Preventive Services Task Force (USPSTF) systematically reviews data regarding screening tests with a focus on benefits and harms. Their recommendations for doctors are designed to guide them in ordering appropriate cancer screening tests. Members of the task force give each test a grade (A,B,C,D) in terms of its overall benefit and potential harm. For example, with some diseases like prostate cancer, it can be difficult to decide what to do when a test comes back positive. There can be risk for overtreatment in the elderly where a prostate cancer may not influence health in the patient’s lifetime. Recently, the USPSTF recommended against prostate screening at any age (grade of D) on the grounds that, in their view, the overall harms outweighed the benefits. This change in the PSA screening has been disruptive for some men who were used to regular PSA screening. One lesson learned in this change is that it can be very difficult for the public to get used to a test for years, and then have it taken away without providing a replacement.
Q: What are the most common cancer screening tests recommended by doctors today?
A: In the United States, there are well-established screening practices for the more common cancers such as breast, colon, cervical tissue, and to a lesser extent today for prostate cancer. The USPSTF recommends routine screening now for breast, colon, and cervical cancer for those at normal risk; but advise that the evidence isn’t sufficient to recommend for or against screening for bladder, oral, and skin cancers.
For colon cancer, the USPSTF gives a strong recommendation for screening from age 50 to 75. Test options include testing the stool for blood or using a scope to look at the colon for tumors or polyps. Screening for cervical cancer is a success story with marked reductions in deaths from that disease since the Pap test was introduced in the 1940s. This is a test that evaluates how cells scraped from the cervix look under the microscope. Screening starts in the 20s and continues until about age 60. Since cervical cancer is a disease related to the human papilloma virus (HPV), screening for HPV is now a part of a cervical cancer screening strategy. Some years ago recommendations for the Pap smear evolved from yearly testing to every three years if recent tests had been normal. This was also a disruptive change that was difficult for the public to accept. It is important to remember that technology and best practices change.
Following a comprehensive review of the science on the benefits and harms of screening mammography, the USPSTF finalized its newest recommendations on screening for breast cancer in January. Screenings are now recommended routinely beginning at 50 with testing every other year for women at average risk. Women at age 40 should have a conversation with their doctor about the wisdom of screening before 50.
While these changes in screening guidelines may, in fact, save money, cost was not the reason for the updated recommendations. The overall balance of benefit versus harm, particularly with breast and prostate screening, was the driver for the changes.
Q: Why are we suddenly hearing about lung screening today?
A: The most recent common cancer where screening may play a role is lung cancer. A large clinical trial compared CT scans to chest x-rays for screening in people who were current or former heavy smokers. The group screened with CT scans had a reduction in death. This is the first really positive lung cancer screening trial. Hospitals or clinics that begin a lung screening effort, like Baystate Medical Center has, should have an organized program with multidisciplinary review of all cases and a thorough collection of data and analysis of outcomes.
Q. What is the final word on cancer screening?
A. What is important to remember is that before a patient is screened, he or she needs to consider what they will do if the test comes back positive for cancer. It’s also important to talk with your doctor about what screening tests are best for you, and when they should begin based on your age, overall risk, and family history.
(Dr. James Stewart, FACP is chief of Hematology - Oncology at the Baystate Regional Cancer Program.)