There’s no question that breast cancer mortality has fallen dramatically over the last several decades. The question is why.
Proponents of cancer screening believe that early detection has played a major role by finding cancer and enabling treatment to start before it spreads.
- But that position is disputed by a vocal minority of skeptics who believe that better cancer treatments deserve most of the credit.
A case in point was the Bretthauer et al study published in 2023, which claimed that there was no evidence to support screening’s beneficial impact on all-cause mortality.
- This despite a demonstrated long-term decline in mortality for the cancers targeted by the four major population-based screening programs: breast, cervical, prostate, and lung.
A new study in JAMA offers clarity in the debate by placing a numeric value on the tools that have contributed to lower breast cancer mortality. Researchers led by Jennifer Caswell-Jin, MD, of Stanford University used simulation models based on CISNET data to analyze breast cancer mortality from 1975 to 2019, drawing the following conclusions:
- Screening and treatment together produced a 58% decline in breast cancer mortality, from a death rate of 48/100,000 women to 27/100,000
- 47% of the reduction was due to treatment of stage I to III cancer
- 29% was due to treatment for metastatic breast cancer
- 25% was associated with mammography screening
The authors also discovered that the biggest improvement in breast cancer survival after metastatic recurrence (3.2 vs. 1.9 years) happened between 2000-2019.
The new results in Caswell-Jin et al should be seen as another victory for the screening community. In addition to setting a numeric figure for screening’s value, they also demonstrate the synergistic effect when screening and treatment work together to target breast cancer before it has a chance to spread. Efforts to separate the two are quixotic at best and dangerous to women at worst.