Hello - I did find the 53% statistic on a particular website (*not* the American Cancer Association), but they did not list a specific research citation. Normally, a credible cite will list the specific study where their statistics came from, so you can verify for yourself.
Interestingly, there was some research released just a couple of weeks ago that found women with a history of hyperthyroidism had an 11% increased overall risk of breast cancer. However, the study left many questions unanswered. For example, which treatment option for hyperthyroidism did the women select? (Since this was in Europe, my guess is the majority of patients received antithyroid meds or surgery). Also, how long were they hyperthyroid before receiving a diagnosis and treatment? In the meantime, the researchers recommend that "women with an overactive thyroid should stay in close communication with their doctors and follow routine breast cancer screening recommendations
Should doctors be talking about this potential risk before patients make a final treatment decision? Yes, absolutely. But it's important to note that all three treatment options have risks and benefits.
I'm sorry that you are going through this, and I'm hoping that other members here who are also survivors will chime in here with their experiences.
EDIT: I tracked down the study where the 53% might
have come from:http://onlinelibrary.wiley.com/doi/10.1002/cncr.22635/full
However, the study noted that, "The hyperthyroidism was caused by Graves disease in 57% (1604) of patients and by nodular thyroid disease (toxic multinodular goiter or toxic adenoma) in 43% (1189). The patients with nodular thyroid disease were older (median age 67 years vs 57 years, P < .001), received a higher cumulative dose of RAI (median dose of RAI, 259 vs 222 MBq, P < .001), and were treated earlier (median year of the first RAI, 1976 vs 1991, P < .001), but were followed as long as those with Graves disease (median follow-up time, 9 years 10 months vs 9 years 2 months; P = .57). The overall cancer incidence was increased in the patients compared with the corresponding control group in both etiologic groups (Table 2). However, the risk of breast cancer (RR, 1.78; 95% CI, 1.07–2.95 vs 1.32; 95% CI, 0.79–2.20) and stomach cancer (RR, 2.38; 95% CI, 1.20–4.71 vs 1.31; 95% CI, 0.49–3.51) was increased only in the patients with nodular thyroid disease but not in those with Graves disease
So even though this study excluded patients with thyroid cancer, it included patients with overactive nodules who received a higher dose of radiation than the Graves' patients - and it looks like that is the group that had the higher risk of breast cancer.