Was my cancer pregnancy related?

Hi. Was wondering what was considered a pregnancy related breast cancer? What I am trying to understand is this:

My son was 18 months old when I discovered my lump?  I want more children.  In some areas of Dr. Susan Loves site I have seen that anytime your cancer is related to your past pregnancy then you shouldn't have more kids?  

I realize that if you find your lump while your pregnant or after having the baby that this is related to the cancer and you shouldn't have future kids. I also realize that if you discover your lump when your child is over 4 years of age then it's probably not related to pregnancy therefore it may be safe to become pregnant again.

Since my son was 18 months old when I found my lump I don't know what to think and seem to be in a grey area.

I have asked if it's safe to get pregnant after stage 1 bc before on a board and the answer was yes.  Then the response said something like in only a few cases has their been  a problem and this is in a situation when the women finds her lump shortly after being pregnant.

My doctors think it's okay to get pregnant as long as I wait 2 years.  I was estrogen postive and will be taking tamoxifen for only 2 years but my doctors feel that is safe since I am stage 1 and desire more children.  I seem to fall under a unique situation though because I have seen lots of women after bc go on to have children but haven't seen many women who already had children before bc have childre after breast cancer.

Do you know of any women who had children before and after bc and was my cancer pregnancy related?

[CCF-RN,MSN-JS]

Dear Camsmomme, Pregnancy-associated breast cancer, which is defined as all breast cancer diagnosed during pregnancy or within the following year, is a relatively rare finding.  Because this is a rare finding there is not a whole lot of information that gives clear data regarding whether the pregnancy itself has any influence whatsoever on the development of the cancer.  Overall, pregnancy is not associated with increased risk of breast cancer.  Again, the recommendation for delay of childbearing is not due to the concern with pregnancy influencing the recurrence of the breast cancer, but to wait this amount of time to delay childbearing until after the time of greatest risk of recurrence of the tumor.  A concern here is if the cancer recurs in the midst of pregnancy, the potential need for delay of treatment, due to risk to the fetus.

In terms of tamoxifen therapy has adverse effects on pregnancy in laboratory animals. No reports exist on the effects of tamoxifen on human pregnancy, so you would not want to be taking tamoxifen during pregnancy.