That "wash" calculation of yours has to be way off - consider:
Givens:
15.1% of breast cancer deaths occur at ages 45-54.
The overall breast cancer survival rate is 89.1%.
The overall breast cancer survival rate without regular mammograms is 44% but with regular mammograms is 95%.
Assume 100,000 women who die of breast cancer at some time in their lives. 15,100 of those will be expected to die at ages 45 - 54.
Those 100,000 would be the unfortunate deaths associated with 917,431 breast cancer diagnoses. The 15,100 deaths at ages 45-54 would be the unfortunate deaths associated with 138,532 diagnoses at the ages of 40-49 assuming the survival rate for those in this age range is the same as the overall survival rate.
If the overall survival rate of those 138,532 diagnoses were reduced from 89.1% to 44%, one would see 77,578 deaths during the age 45-54 periods instead of 15,100. That is, 62,478 more deaths.
Now total breast cancer deaths will be 162,478 instead of 100,000. The overall survival rate would now be 82.3%, iow lower by 6.8%. That would be the expected impact of eliminating mammograms entirely for the 40-49 age group. Cutting mammograms in the selected age group in half, one could surmise would produce perhaps half as big a reduction as calculated, say 3.4%. |
