John D. Keen MD, MBA, Presenter: Nothing to Disclose

James E. Keen PhD, DVM, Abstract Co-Author: Nothing to Disclose

To expand the concept of informed medical decision making regarding screening, we calculated the average life expectancy for a woman diagnosed with breast cancer. We derived the percentage life expectance (PLE) by dividing this average by the normal life expectancy. For comparison, we calculated the PLE for patients with other types of cancer.

We obtained the life expectancy for patients with invasive breast cancer and ductal carcinoma in situ (DCIS) by using Surveillance Epidemiology and End Results (SEER) survival statistics prior to and after widespread population screening. For lung, ovarian, colon, cervical, and prostate cancer we used the most recent SEER 10 year survival data for diagnosis in 1993. We applied the gamma mixed-exponential (GAME) method to estimate life expectancy for the average cancer patient using United States life tables for women and men in 2003. We applied the declining exponential approximation for life expectancy (DEALE) for DCIS.

A woman age 50 has a normal life expectancy of 32.4 years, and if diagnosed with invasive breast cancer after no screening she can expect to live at least 20 years, or 61% of her normal life expectancy. This survival is based on 1980 breast cancer therapy. At age 40 and 60, the PLE values are 59% and 64%. The age 50 PLE for 1993 survival data is 77%, which reflects the effects of screening bias, screening benefit, and better therapy. The pre-screen PLE for DCIS is 90%, or 29.2 years. For comparison, a 50 year old woman diagnosed with invasive lung, ovarian, colon, and cervical cancer has a PLE of about 11%, 36%, 51%, and 71%. A 50 year old man with lung, colon, and prostate cancer can expect to live 10%, 54%, and 96% of his normal life expectancy of 28.5 years.

A woman diagnosed with invasive breast cancer will live on average about two-thirds of her normal life expectancy assuming she does not get screening, similar to cervical cancer patients. Women with DCIS have a similar outcome to a man with prostate cancer.

Life expectancy estimates may be a convenient way to present cancer lethality and the relationship between diagnosis risk and death risk before screening, and thus support informed decision making.

Keen, J, Keen, J, If I Choose Not to Participate in Regular Screening Mammography How Long Will I Live If I Develop Breast Cancer?.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6005339.html