I remember reading something about this a while back. Here's what I found, in a search on google, fwiw:

According to a Jan., 2004 Journal of Applied Toxicology editorial:

    The findings of parabens in tumour samples are additional results in line with the general hypothesis that there may be a link between oestrogenic compounds commonly used in underarm cosmetics and other consumer products and breast cancer. The results alone, however, do not suggest that these chemicals caused the tumours in these patients. Darbre et al.'s findings invite several questions: how did the parabens get into the breast, are they persistent and could they do harm? The answers require further research.