Screening for Lung Cancer & Breast Cancer

My prior post revealing new research about screening for lung cancer and breast was the mostly good news from the American Cancer Society. It notes a 25-year trend of decreasing death rates for common cancers. Much of the decrease was due to advances in treatment, but it makes sense that early detection makes treatment less complicated, with more favorable results. That's why everyone should know and follow recommended NCI cancer screening guidelines for the two most common cancers: lung cancer and breast cancer. 

Cancer deaths by site

Lung Cancer Screening

Lung cancer, usually due to cigarette smoking, has been the most common cause of cancer death for many years. Low dose CT scan of the lung can discover lung cancer at an earlier stage, and has been found to reduce lung cancer deaths by 20% in current and former smokers. But less than 4% of the 8.7 million eligible smokers had CT scan of the chest to check for lung cancer in 2010.  In January 2017, a report of over 2000 prior smokers who were screened with low-dose CAT scan detected lung cancer in 1.5%.  Over 40% had other abnormal findings including emphysema, pulmonary nodules and coronary artery calcification which required medical follow-up.

Breast Cancer Screening

The death rate for breast cancer in women has dropped 38% in the past 25 years. While much of this decrease was due to advances in cancer therapy, breast cancer screening by mammography with detection of cancer at an earlier stage has been important. However, in talking to my patients recently, I see confusion about the value of mammograms, what age to begin and stop, and concern about potential harm. Much of this is based on a poorly done Canadian medical study, widely reported in the media, challenging the benefits and emphasizing the harm of mammography. Unfortunately, criticism of these conclusions aren't as well known. For the record, here is the statement of benefit from the National Cancer Institute:

In the randomized controlled trials, for women aged 40 to 74 years, screening with mammography has been associated with a 15% to 20% relative reduction in mortality from breast cancer.

No medical study of mammography included women over age 74. Is screening mammography is beneficial in these women? Some breast cancer screening guidelines exist, but recommendations vary. Most doctors (myself included) will suggest screening mammography to older women who have a life expectancy of at least 5 years.