Should I take tamoxifen to reduce the risk of a new tumor if my breast tumor does not have hormone receptors?

No. At this time, we don't have any research evidence showing benefit of tamoxifen if your breast cancer was negative for the estrogen and Progesterone receptor. Tamoxifen has risks (blood clots, stroke, uterine cancer) and side effects, so it should not be taken without a good reason.
No. If your cancer is er negative, it will most likely not be recommended by your oncologist.
Controversial. This is a great question, probably best answered with your cancer doctor. The issue is that we don't use tamoxifen for treatment of er- breast cancers but we use it for prevention of people at high-risk; as a breast cancer survivor, you would qualify in this latter category. Even though you are more likely to develop a second ca that is er-, tamoxifen may lead to an earlier diagnosis.

Related Questions

Is combined tamoxifen plus hormonal therapy better for breast cancer?

No. Studies show that adding tamoxifen to an aromatase inhibitor (what i assume you mean by "hormonal therapy") was not better than either drug alone. Read more...
Tamoxifen only. For tumors that are estrogen positive, tamoxifen is the hormonal treatment for women that are premenopausal. If you are post menopausal, then aromatase inhibitors are the equivalent. We do not give additional hormones because the goal is to limit the amount of estrogen. Read more...

Is combined tamoxifen plus hormonal therapy better for breast cancer in pre or postmenopausal women?

Need to know. Er/pr receptor status on resected tumor, as if these are negative, no role for hormone therapy. Post orpre-menopausal er+ patients are treated with the effective, cheap, low adverse effect tamoxifen, a useful drug for more than 30 years. But ovarain function precluses use of anastrazome or the newer more expensive letrozole. These all work; toxiicty and cost vary. Read more...
Hormonal treatment. In general, tamoxifen is used for premenopausal women and aromatase inhibitors are used for postmenopausal women. Read more...
Estrogen supression. In general, aromatase inhibitor is only indicated for postmenopausal women ;not for premenopausal; while on the other hand, tamoxifen can be given either in pre or postmenopausal. Only thing is that tamoxifen can cause a little bit higher risk for complication -i.e. Risk for blood clots and risk for develping uterine cancer- when used in older population- age of -65 Y.O. Or above. Read more...