CT Screenings Can Reduce Lung Cancer Mortality

A study published in the New England Journal of Medicine, focused on data from 13,195 men and 2,594 women aged 50 to 74 years old who were heavy smokers, found that participants had a lower mortality if they were screened with computed tomography (CT).

All individuals were followed for a minimum of 10 years and each was randomly assigned to get either low-dose CT scans at baseline, a year, three years and 5.5 years, or no screenings at all. Participants who were screened had lower death rates than the control group: 24% lower for men and 33% lower for women.  The overall referral rate for suspicious nodules was 2.1%.

A U.S. trial of nearly 54,000 heavy smokers in 2011 also found a 20% drop in lung cancer deaths via screenings with CT in comparison to chest X-rays. 

Following the U.S. study, the U.S. Preventive Services Task Force recommended low-dose CT screening for people aged 55 to 80 who had a history of smoking equal to a pack a day for 30 years and were either still smoking or had quit within the past 15 years. 

The American Cancer Society states that lung cancer is responsible for 25% of all cancer deaths and estimates that 72,500 men and 63,220 women in the U.S. are expected to die of lung cancer in 2020

USPSTF guidelines for breast cancer screening

On April 20, 2015, the U.S. Preventive Services Task Force (USPSTF) released its draft guidelines for breast cancer screening.

The USPSTF recommends biennial screening mammography for women ages 50 to 74 years.

The decision to start screening mammography in women prior to age 50 years should be an individual one. Women who place a higher value on the potential benefit than the potential harms may choose to begin biennial screening between the ages of 40 and 49 years.

•   For women at average risk for breast cancer, most of the benefit of mammography will result from biennial screening during ages 50 to 74 years. Of all age groups, women ages 60 to 69 years are most likely to avoid a breast cancer death through mammography screening. Screening mammography in women ages 40 to 49 years may reduce the risk of dying of breast cancer, but the number of deaths averted is much smaller than in older women and the number of false-positive tests and unnecessary biopsies are larger.

•   All women undergoing regular screening mammography are at risk for the diagnosis and treatment of noninvasive and invasive breast cancer that would otherwise not have become a threat to her health, or even apparent, during her lifetime (known as “overdiagnosis”). This risk is predicted to be increased when beginning regular mammography before age 50 years.

•   Women with a parent, sibling, or child with breast cancer may benefit more than average-risk women from beginning screening between the ages of 40 and 49 years.

•    The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening mammography in women age 75 years and older.

•     The USPSTF concludes that the current evidence is insufficient to assess the benefits and harms of tomosynthesis (3-D mammography) as a screening modality for breast cancer.

This recommendation applies to asymptomatic women age 40 years and older who do not have pre-existing breast cancer or a previously diagnosed high-risk breast lesion and who are not at high risk for breast cancer because of a known underlying genetic mutation (such as a BRCA mutation or other familial breast cancer syndrome) or a history of chest radiation at a young age.

Controversy and Screening Mammography

Currently the AmericanCancer Society, the American College of Radiology and Society of Breast Imaging recommend that women age 40 and over should have annual screening mammography and should continue as long as they stay in good health.  While several international societies such as the Hellenic Society of Breast Imaging follow the above mentioned recommendations, the U.S. Preventive Services Task Force in their circular issued in November and updated in December 2009 recommends screening mammography every two years starting at age 50 to 74.  

In a follow up article, the British Medical Journal published 34 commentaries regarding the study “Twenty five year follow-up for breast cancer incidence and mortality of the Canadian National Breast Screening Study: randomized screening trial” by Miller AB, Wall C, Baines CJ, To T and Narod SA published on February 11, 2014.  Their study that was summarized in my previous post concluded that annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available.  They also found an over-diagnosis of 22%.

As the Canadian National Breast Screening study is a prospective and randomized trial, it will influence medical and lay thinking, it is therefore important its findings and all 34 thoughtful comments and rebuttals should be studied carefully before practitioners and specialists alike formulate an opinion and deviate from the current recommendations by medical societies with expertise in breast cancer.