I personally am into the "first, do no harm." I stay away from plastics, radiation (including mammograms, actually). You can do your own research and or review items on this blog about survival rates of people who have mammograms regularly versus those who do not. I also think it's important to factor in the stress and things of having these procedures done plus the inevitable and common false negatives (my mom just had one--and they took 5 more mammos just to confirm that they screwed up...) that ratchet up the anxiety factors.
This article also puts monthly self exams in another perspective.
Two large studies looking at a total of more than 388,000 women found that death rates from breast cancer were the same among women who rigorously self-examined as those who did not, while there were almost twice the number of biopsy operations in the self-examination group.
According to some experts, the best way for a woman to check her breasts is not to follow a strict examination routine, but to get to know what is normal, and feel them regularly for signs of any changes.