Early Detection Saves Lives: Updates on Cancer Screening

Michelle Nguyen, PharmD BCOP
Clinical Pharmacy Manager, Medical Oncology
New York-Presbyterian Hospital, Columbia University Irving Medical Center
New York, NY 

Overall cancer mortality has decreased by 25% from 1990 to 2015 in the United States, which can be attributed to greater awareness of cancer screening in the general population.¹ The American Cancer Society (ACS) and the U.S. Preventive Services Task Force (USPSTF) provide cancer screening recommendations each year, with the aim of increasing the likelihood of benefits and limiting the harms from screening. The annual report updates previous recommendations, provides data on cancer screening rates, and discusses issues related to early cancer detection. Through early detection by screening, death rates have been reduced in cancers of the breast, uterine cervix, colon, rectum, prostate, and lung.

Breast Cancer Screening

Female breast cancer death rates have been decreasing since 1989 in the United States through early detection by mammography.² The goal of screening mammograms is to detect breast cancer early, but this comes with risks because there may be false-positive findings. Providers have debated what age is appropriate for the initiation of a mammography. In 2015, experts offered more guidance on this issue and provided their recommendations in the updated ACS breast cancer screening guidelines. The recommended primary screening exam for average-risk women is an annual mammography starting at age 45. The risk among women aged 40–44 years was lower and more similar to the risk among women in their late 30s, leading the ACS to not make any direct recommendations for screening in this population. Therefore, women aged 40–44 years are encouraged to choose whether to screen earlier than age 45. Women aged 55 or older have the option to transition to biennial screening or continue screening annually. Mammography screening should continue as long as the patient’s overall health is good and life expectancy is 10 years or longer. In addition to the discussion on screening mammograms, breast exams—either self-exams or exams from a medical provider—are no longer recommended by the ACS because research did not show any clear benefit.³

Cervical Cancer Screening

Cervical cancer incidence and mortality rates have markedly decreased over the decades in the United States, with most of the reduction attributed to screening with the Pap test. The number of deaths declined from 2.8 to 2.3 deaths per 100,000 women from 2000 to 2015.⁴ Vaccination and routine cervical cancer screening are essential in preventing this disease: approximately 70% of human papillomavirus (HPV)–related cancer cases can be prevented with vaccination. The Advisory Committee on Immunization Practices (ACIP) revised its HPV vaccine schedule in 2016 from a three- dose schedule to a two-dose schedule for patients younger than 15 years. The change was prompted after antibody responses for the two-dose schedule were shown to be noninferior to those for young women who received all three doses. In addition, the U.S. Food and Drug Administration approved the use of the HPV vaccine in men and women up to age 45; however, no changes in guidelines have been made, and insurance plans may not cover the vaccine administration after age 26.⁵

In 2018, the USPSTF updated its recommendation to offer three screening options for women. Women aged 30–65 years may choose the following screening strategies: Pap-only testing every 3 years, high-risk HPV-only testing every 5 years, or co-testing every 5 years. This differs from recommendations by the American College of Obstetricians and Gynecologists and the American Society for Colposcopy and Cervical Pathology for co-testing every 5 years, with alternative options of Pap-only or HPV-only testing every 3 years. The new recommendation by the USPSTF was implemented after its review of randomized and observational studies. It was noted that both co-testing and high-risk HPV testing offer similar cancer detection rates: each prevents one additional cancer per 1,000 women screened as opposed to Pap-only testing.⁵ The USPSTF continues to recommend triennial cervical cytology for women aged 21 to 29 years.⁴ The most critical aspect of screening is getting all women screened—regardless of which method is used.

Colorectal Cancer Screening

An accelerated decline in colorectal cancer incidence rates occurred during the past decade, which may be attributed to the increased uptake of screening and removal of precancerous lesions. In the 2018 update, the ACS lowered the age to start screening average-risk people to age 45. This new recommendation was made because of the emergence of new data that showed increasing rates of colorectal cancer in younger populations. The study found that colon and rectal cancer rates had increased by 0.5% to 2% per year from the mid-1990s through 2013 for adults aged 40–54 years. Regular colorectal cancer screening should continue through age 75 if the person is in good health and has a life expectancy of more than 10 years. Different screening options are available, and adults may choose one of the following methods: guaiac-based fecal occult blood test or fecal immunochemical test every year, multitarget stool DNA test every 3 years, flexible sigmoidoscopy every 5 years, colonoscopy every 10 years, or CT colonography every 5 years. For adults older than 85 years, colorectal cancer screening is no longer recommended.⁶

Prostate Cancer Screening

In the United States, the lifetime risk of being diagnosed with prostate cancer is approximately 11%, with a 2.5% lifetime risk of dying. The USPSTF stated in the 2018 update that men aged 55–69 years should decide whether to undergo periodic prostate-specific antigen (PSA) screening for prostate cancer after discussion with their provider. The main difference is the update to the recommendation grade from D in the 2012 USPSTF recommendation to C in the update. The change in recommendation grade is based on additional evidence that increased the USPSTF’s certainty about the reductions in risk of dying of prostate cancer and risk of metastatic disease. Longer-term follow-up of the European Randomized Study of Screening for Prostate Cancer trial found that PSA-based screening for prostate cancer prevents 1.28 men from dying of prostate cancer for every 1,000 men screened. However, men should be advised that screening offers a small potential benefit. Studies continue to demonstrate the harms of PSA-based screening, including false-positive results, overdiagnosis, and overtreatment. The intention of the USPSTF update is to promote the importance of informed decision making prior to screening.⁷

Lung Cancer Screening

Lung cancer is the leading cause of death from cancer in men and women. This tumor type accounted for an estimated 154,050 deaths in 2018, approximately 26% of all cancer deaths in the United States. Among men, mortality rates have declined by 43% since 1990, and among women, mortality rates have declined by 17% since 2002.² In the 2013 ACS lung cancer screening guidelines, the recommendation for screening was unclear. Therefore, the ACS clarified this recommendation in the 2017 update by stating that annual screening for lung cancer with low-dose computed tomography (CT) is recommended in adults aged 55–74 years who have a 30 pack/year smoking history and currently smoke or have quit within the past 15 years.² The USPSTF has a broader age range for lung cancer screening, with recommendations for adults up to age 80 based on modeling studies.⁸

Adults should recognize the importance of cancer screenings and be reminded when they are due for them. By increasing awareness of regular screening, cancer deaths can continue to decline in the United States.

References

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