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May 30, 2019 11:09AM
Beesy, most doctors quote numbers like 4% or 7%, in terms of the odds of someone with breast cancer being diagnosed a second time. If those numbers are correct, then it would be true that it's uncommon to develop a new primary. But there is a lot of inconsistency in the data, and after doing quite a bit of digging around on the subject, I've come to the conclusion that those numbers are simply not accurate.
Here's one study that all on it's own perfectly highlights the data inconsistencies: Second Primary Breast Cancer Occurrence According to Hormone Receptor Status
The very first line of the article states that "Contralateral second primary breast cancers occur in 4% of female breast cancer survivors". Well, that's certainly a low risk. But Oops!, the analysis then goes on to conclude that:
"Women who had survived HR-positive (i.e. ER+ and/or PR+) breast cancers had more than a twofold increased risk of a second primary tumor, and women who had survived HR- breast cancers had nearly a fourfold increased risk, compared with the age-, race-, and year-adjusted general population.".
So the report tells us that 1 in 25 (4%) breast cancer survivors will develop a contralateral breast cancer, but then explains that the risk is at least double that of the general population. As we know, the breast cancer risk for the general population is 1 in 8 (12.5%). Huh?
I believe the disconnect in the figures is due to the fact that: 1) most studies that evaluate the rate of contralateral breast cancer cover a relatively short time period, 5 years or at most 10 years; 2) most studies don't account for the fact that approx. 30% of breast cancer survivors have a BMX at the time of their first diagnosis, bringing their risk level down to just 1%-2%; 3) some studies look only at contralateral cancers and don't include new primaries that occur in the same breast as the original cancer; and 4) most studies don't factor in the mortality rate of breast cancer patients from other causes.
As more women are being diagnosed at a younger age, as more women are surviving their first diagnosis, as more women are living longer, and as more women have been taking endocrine therapy which offers a degree of contralateral protection for 7 - 8 years (based on 5 years of Tamoxifen or an AI), I believe we are starting to see a much higher rate of new primaries among breast cancer survivors who are 8+ years out, including many who are even 20+ years out. I know the women on this board are not a representative sample, but most of the second primary breast cancers I recall seeing over the past few years have occurred well beyond the time frame of most of the studies that have found such low contralateral breast cancer rates. So most of the women here would not even be included in the count. And all of the factors I mentioned would raise the rate of new primaries to well above 4% and more into the range of 'double the risk' of the average woman. And that's what the study actually found.
BCBB, my apologies for taking your thread off onto a tangent.
Dx 9/15/2005 Right, 7cm+, DCIS-Mi, Stage IA, Gr 3, 0/3 nodes, ER+/PR- ** Dx 01/16/2019 Left, 8mm, IDC, Stage IA, Gr 2, 0/3 nodes, ER+/PR-, HER2- (FISH) ** Surgery 11/30/2005 MX Right, 03/06/2019 MX Left ** Hormonal Therapy 05/2019 Letrozole