Opinion ID: 2367601
Heading Depth: 1
Heading Rank: 5

Heading: The parties' causation theories

Text: Expert testimony was presented from both sides regarding the cause of respondents' breast cancer. Respondents argued and presented evidence that, but for ingesting estrogen plus progestin, they would not have developed cancer. Wyeth countered that the cause of respondents' cancer is unknown, that the prescribed hormone therapy drugs did not cause their cancer, and that respondents had other risk factors for breast cancer. Respondents' epidemiologist and oncologist testified that breast cancer can be caused either by initiation, where an agent damages a cell's DNA and causes the first abnormality, or by promotion, when a substance, such as Wyeth's hormone-therapy drugs, causes an already existing abnormal cell to grow from a benign lesion into cancer. The oncologist testified that hormone-deficient women, such as respondents, have a lower risk of developing hormone-receptor-positive breast cancer after menopause. The expert testified that the risk is low because hormone-deficient women's bodies lack sufficient hormones to cause abnormal cells to grow into cancer. The oncologist stated that once the stimulus, i.e., hormone replacement drugs, are removed, the hormone-positive tumors shrink. On cross-examination, respondents' epidemiologist testified, however, that after menopause, a women's chance of developing cancer increases even while the woman's hormone levels are naturally decreasing. Thus, according to the epidemiologist, the presence of an estrogen receptor does not consistently determine that a tumor's growth was caused by the estrogen receptor. Respondents argued that the WHI study demonstrated that the rate of breast cancer with the use of hormone replacement therapy had a quadrupling of the relative risk; consistent with earlier studies, the WHI study initially indicated a relative risk of 1.24, but further analysis of the WHI study showed a 4.61 relative risk for women who took estrogen plus progestin for more than five years. Respondents' experts explained that this discrepancy occurred because not every woman who enrolled in the study abided by its terms. In other words, the 1.24 relative risk took into account the total number of women who enrolled in the study, but the 4.61 relative risk included only those women who stayed in the study and took the medication as directed. Wyeth acknowledged the risk, but insisted that the relative risk was only 1.24, which was less than the 1.3 to 2.0 risk that it provided in Prempro's warning label. Respondents' oncologist also testified that respondents' tumors were studied and showed the presence of estrogen and progestin receptors. Thus, the oncologist testified that respondents' breast cancer was caused by hormones, as they had developed estrogen and progestin receptor-positive breast cancer. Respondents argued that because they introduced hormones into their bodies, through the prescribed hormone therapy drugs, they were put at a greater risk for developing hormone-positive breast cancer. According to respondents' oncologist, but for taking the hormone therapy drugs, respondents would not have developed cancer. Wyeth solicited evidence from respondents' oncologist and epidemiologist that science does not know exactly what causes breast cancer and that respondents had other risk factors for developing breast cancer. The specific risk factors included respondents' gender, their age, the denseness of their breasts, that each woman was a long-time smoker, that they all had previous biopsies to remove benign lesions, and the overall number of years that the women had menstrual cycles. Respondents' experts also testified on cross-examination that all three women had abnormal cells before taking the hormone replacement therapy. Respondents Rowatt and Forrester had an additional risk factor: they were both overweight. Testimony also showed, however, that respondents' physicians did not believe that respondents were at risk for cancer because they had no family history of breast cancer and none of them had ever taken birth control. Respondents' oncologist, on direct examination, discounted the majority of respondents' existing risk factors. The expert testified, for instance, that respondents' dense breast tissue would not be a significant risk factor, as during menopause women tend to lose density in their breasts. On cross-examination, the oncologist conceded, however, that the same is not true for every woman. Respondents' oncologist and Wyeth's radiology expert disagreed as to whether respondents' breast density had changed while on hormone replacement therapy. Respondents' epidemiologist and cancer biologist physician testified that it could be anywhere from a few to 40 years for a benign lesion to turn into cancer. The oncologist explained that respondents' cancers were not detectable for years because the women did not have preexisting cancer cells. Thus, in respondents' case, it took years for the estrogen-progestin drug combination to fertilize respondents' abnormal cells and develop the cells into cancer. Further expert testimony was presented that recent medical literature confirmed that estrogen-progestin-receptor-positive cancers have an even higher statistical chance of recurrence than other breast cancers. At the time of trial, none of respondents' breast cancer had spread, and respondents were in remission.