A 74-Year-Old Man With Questions About Colorectal Cancer Screening
Ronald N. Rubin, MD—Series Editor
Rubin RN. A 74-year-old man with questions about colorectal cancer screening. Consultant. 2019;59(2):50-52.
A 74-year-old man had changed health care providers and presented for his initial office visit. He had more or less routinely seen a physician twice yearly for the past several years. He related that he was in his usual state of health, which was quite acceptable to him and included type 2 diabetes mellitus of many years’ duration, managed with metformin, and chronic obstructive pulmonary disease resulting from having smoked as a younger man, treated with inhalers. He had stopped smoking 20 years ago.
He reported having had some “bad experiences” with procedures and hospitals, including a serious infection following a biopsy after an elevated prostate-specific antigen test result approximately 15 years ago as part of a screening program sponsored by his golf club. He had no new symptoms or signs after a comprehensive review of systems was performed.
He brought with him his last set of laboratory test results, obtained approximately 6 months ago. A complete blood cell count showed a hemoglobin of 15.8 g/dL, a mean corpuscular volume of 94 µm3, and a normal red cell distribution width. Serum ferritin was 88 ng/mL, hemoglobin A1c was 6.0%, creatinine was 1.9 mg/dL (estimated glomerular filtration rate, 46 mL/min/1.73 m2), arterial oxygen saturation was 92% on room air, and forced vital capacity of 2.1 L.
Physical examination revealed a man who appeared to be his stated age with a suggestion of slight plethora of the face. Vital signs were normal. Cardiac examination showed regular rhythm, 88 beats/min without murmur or gallops. Chest examination revealed a degree of prolonged expiration and sporadic end expiratory wheezes. Examination findings were otherwise normal.
During the evaluation, a discussion about cancer screening ensued. He was quite aware of the lay literature regarding screening for prostate, lung, and colon carcinoma. He had no family history of any of these. Based on his personal viewpoint and experience with procedures and hospitals related to cancer screening, he simply did not want a colonoscopy but was willing to consider alternatives for colorectal cancer screening.
Answer: D, stool FIT testing annually.
The essential requirements for effective screening to prevent a specific cancer are as follows: (1) for the screening scheme to accomplish a statistically and clinically significant reduction in cancer deaths specifically and, hopefully, in overall mortality in the screened population; (2) for there to be clinical trials with a control group (unscreened) to provide strong data; (3) for the screening scheme to be sensitive and specific to a large degree; and (4) for the scheme to be safe regarding complications, as convenient as possible, and, in our current era, at least somewhat cost-effective.
Several common (or in the case of cervical cancer, once-common) cancers now have screening methods that fulfill all or at least most of these criteria, and this clinical vignette relates to one of them: colorectal cancer (CRC) screening. The potential answers offered above are an array of currently available screening methods for CRC. In our patient’s case, the gold standard for CRC screening—colonoscopy, which has been proven in good clinical trials to reduce CRC mortality by 68%1—has been ruled out by patient preference. Colonoscopy also has the advantage of detecting precancerous lesions, and since normal colonoscopy findings result in a 10-year period before being repeated, it is competitive on a cost-effective basis, too. The negatives include its invasive nature, the need for a full bowel preparation, and a small increase in the incidence of serious complications compared with the less-invasive techniques.1 Given that serious complications from a procedure are more prevalent in the elderly, and since the need for CRC screening becomes more of a gray area when comorbidities and an age above 75 are present, it is not so terribly unreasonable for our average-risk patient to refuse colonoscopy and for us to consider other methods.
The default screening method with the most efficacy, convenience, safety, and cost-effectiveness is fecal occult blood testing (FOBT), which can be problematic depending on reagent, since animal blood or foods such as horseradish will react to guaiac, or much more preferably FIT, which uses antibodies to detect blood.1,2 FIT testing has high sensitivity (79%) and even higher specificity (94%) for CRC detection and is repeated annually. Remember, however, it requires mucosal bleeding and thus misses precancerous lesions that have not yet done so.2 Thus, Answer D is the preferred option in our patient’s case. In fact, current recommendations from the US Multi-Society Task Force of Colorectal Cancer include FIT testing in first-tier screening.3
Flexible sigmoidoscopy (Answer A) is more invasive, still requires at least limited bowel preparation, and has shown a lesser (27%) reduced mortality than FIT testing.1 It seems an intermediate strategy in terms of efficacy and convenience, being nowhere near as effective as colonoscopy and certainly no better than FIT, yet being more invasive, prone to endoscopy-related complications but without the efficacy benefit. Therefore, particularly in our patient’s case, flexible sigmoidoscopy is not optimal. The Task Force recommendations consider flexible sigmoidoscopy essentially a second-tier screening option.3
FIT-DNA testing (Answer B) has the advantage of being a home test that rather than testing for the presence of blood in the stool tests for abnormal DNA from cancerous cells shed into the stool. As a newer test, there are far fewer studies available for analysis. There are some data that suggest an increased sensitivity compared with FIT alone (92.3% vs 73.8%) but at the cost of an equivalently lowered specificity (86.6% vs 94.9%).1,4 To date, the effect on mortality (FIT-DNA testing was compared with colonoscopy, not in an unscreened population) remains unknown, and using autogenetic testing makes it more expensive than the first-tier group of FOBT, FIT, and colonoscopy. Thus, like sigmoidoscopy, FIT-DNA testing is in the second tier,3 and it would not be considered optimal here.
Finally, CT colonography (Answer C) is a radiologic study using a contrast agent to image the colonic lumen and the colon itself. Again, its efficacy has only been compared with colonoscopy (usually in the same patient), so its effect on mortality remains unknown. It can detect precancerous, nonulcerated lesions such as adenomas but will miss any lesions that are sessile and flat. Other significant negatives include the need for a full bowel preparation (still one of the most problematic features of colonoscopy, sigmoidoscopy, and colonography), is quite expensive compared with colonoscopy and fecal testing, and requires exposure to a contrast agent. Note that the patient in the presented case has a borderline high serum creatinine and decreased creatinine clearance, potentially making exposure to contrast even more problematic. In a standard-risk population, CT colonography also is assigned second-tier status3 and is not the optimal choice here.
It must be remembered, however, that any screening modality is superior and preferred to no testing at all. Choosing from among the available tests requires balancing efficacy, adverse events data, cost, convenience, and patient preference to arrive at the “optimal” choice for the patient in front of us.5
The patient was considered as having average risk for CRC. The array of screening methods was discussed, and when patient preference, comorbidities, and effectiveness were all considered, there was agreement that the best fit was, indeed, FIT testing annually. His initial FIT test results were negative for CRC.
THE TAKE-HOME MESSAGE
CRC screening has an excellent record of efficacy in cancer prevention, with an acceptable risk of adverse effects and complications. Along with screening for cervical and breast carcinoma, CRC screening is one of the great success stories in cancer detection and prevention. The mainstay screening techniques are fecal testing, with FIT being preferred given its lower associated rate of false positivity and that CRC morality is lowered by 32%. Although colonoscopy can double that degree of lowering, there are large cost, convenience, and complication (although uncommon) differences between the 2 screening methods. Other methods are used but do not have the track record of proven efficacy of fecal testing or colonoscopy. Once a patient reaches 75 years, age and comorbidities lessen the mortality benefit such that the decision to screen at all, and by which method, should be tailored individually. What is clear is that any method of screening is superior to no screening, and that a favored protocol should not be forced on a reluctant patient.
Ronald N. Rubin, MD, is a professor of medicine at the Lewis Katz School of Medicine at Temple University and is chief of clinical hematology in the Department of Medicine at Temple University Hospital in Philadelphia, Pennsylvania.
1. Inadomi JM. Screening for colorectal neoplasia. N Engl J Med. 2017;376(2):149-156.
2. Lee JK, Liles EG, Bent S, Levin TR, Corley DA. Accuracy of fecal immunochemical tests for colorectal cancer: systematic review and meta-analysis. Ann Intern Med. 2014;160(3):171.
3. Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2017;153(1):307-323.
4. Imperiale TF, Ransohoff DF, Itzkowitz SH, et al. Multitarget stool DNA testing for colorectal-cancer screening. N Engl J Med. 2014;370(14):1287-1297.
5. van Hees F, Saini SD, Lansdorp-Vogelaar I, et al. Personalizing colonoscopy screening for elderly individuals based on screening history, cancer risk, and comorbidity status could increase cost effectiveness. Gastroenterology. 2015;149(6):1425-1437.