Despite the weak association, these studies have given pro-choice supporters a headache. So much so that the National Cancer Institute (NCI) even issued a press release indicating that weak association epidemiology was not very reliable.
Of course, NCI thinks that weak association epidemiology is bad only in the context of abortion. For anything else, weak association epidemiology is just hunky-dory!
In this fine tradition, Daling et al. pull off a remarkable feat by both repudiating their own abortion-breast cancer link while asking for more money to study it.
Daling et al. interviewed 1,302 women with breast cancer about their reproductive histories, including induced abortion, and reported that:
Women who had been pregnant once and had an abortion had a 20 percent higher rate of breast cancer than women who had no abortion (95 percent confidence interval, 0 percent to 50 percent).
Usually, when public health researchers report their results, they FIRST try to SUPPORT their results and then, almost as an afterthought, point out flaws and weaknesses as an afterthought. Not Daling et al.
The very first sentence in the discussion section is
Some possible limitations of our study warrant discussion.
Daling et al. then go on to discuss how they were able to directly interview only about 80 percent of the women in their study. And they question the accuracy of the responses from their own interviews. Then they state
Although a positive association has been seen in a number of studies that have focused on young women, the overall magnitude is not so great that the possibility of bias... can be excluded.
Funny, I can remember how a reported 30 percent increase in lung cancer risk associated with second-hand smoke was SO definite and meaningful to the public health research crowd. But a 100 percent increase in breast cancer risk from abortion "is not so great"?
Then Daling et al. close with their shameless pitch and not-so veiled threat for more research funding on this issue:
Nonetheless, as additional studies are carried out [shameless pitch] among cohorts of women who have had legal abortions available to them for most of their lives,... there is reason to hope that in the future we [where future funding should go] will have a better understanding of the possible role of induced abortion [not-so veiled threat] in the etiology of breast cancer.