Let’s get this out of the way: both are clearly important. Within appropriate screening, patients don’t get the treatment they need. Further, delayed screening can make treatments less effective if the cancer has progressed or metastasized. On the other hand, without effective treatment, screening won’t have a major impact on patient outcomes.
The question is, which one is more important? The question is not just of academic nature. Funders such as the National Cancer Institute, NIH, foundations, employers and health plans need to determine where they should focus their money: paying more for increased screening or for innovative treatments.
A recent paper by Plevritis et al. (2018) aim to answer this question for patients with ER/ERBB2-specific breast cancer. The authors use six Cancer Intervention and Surveillance Network (CISNET) models and measured the effects of changes in screening and innovative treatments on US breast cancer mortality from 2000 to 2012. They find the following:
In 2012, the estimated reduction in overall breast cancer mortality rate was 49% (model range, 39%-58%) relative to the estimated baseline rate in 2012 of 63 deaths (model range, 54-73) per 100 000 women: 37% (model range, 26%-51%) of this reduction was associated with screening and 63% (model range, 49%-74%) with treatment. Of the 63% associated with treatment, 31% (model range, 22%-37%) was associated with chemotherapy, 27% (model range, 18%-36%) with hormone therapy, and 4% (model range, 1%-6%) with trastuzumab.
Note that the relative importance of screening compared to treatment varied by molecular subtype. On average, however, about 60% of improved survival gains were associated with innovative treatments. Previous studies have also found that treatment advances make up the majority of survival gains, ranging between 75% and 100% of gains for the years between 1988 and 2000.
- Plevritis, Sylvia K., Diego Munoz, Allison W. Kurian, Natasha K. Stout, Oguzhan Alagoz, Aimee M. Near, Sandra J. Lee et al. “Association of Screening and Treatment With Breast Cancer Mortality by Molecular Subtype in US Women, 2000-2012.” Jama 319, no. 2 (2018): 154-164
Sun, Eric, Anupam B. Jena, Darius Lakdawalla, Carolina Reyes, Tomas J. Philipson, and Dana Goldman. “The contributions of improved therapy and earlier detection to cancer survival gains, 1988-2000.” In Forum for Health Economics & Policy, vol. 13, no. 2. De Gruyter, 2010.