I have endometriosis. i have gone through 4 ivf cycles. i want to get the fifth done but i've heard that uterus cancer can be triggered because of endometriosis. i am afraid. what should i do?

Unrelated issues: Ivf, endometriosis and uterine cancer are not causally related. You should communicate your concern to your doctor so that she/he may monitor you closely.

Talk to your doctor: Talk to your fertility specialist about your concerns - a short answer isn't enough. Having said that endometriosis is a risk factor for ovarian cancer rather than uterine cancer, but ovarian cancer is very rare in women of reproductive age. If your fertility specialist is concerned s/he will consult a gynecologic oncologist. Pcos with very irregular cycles increases the risk of uterine cancer.

No reason: I am not aware of anything linking ivf to uterine cancer. However, women with endometriosis have a 2x risk lifetime of ovarian cancer. So i don't think you need to worry about that. But it is unusual to not be pregnant after 4 cycles of ivf and the prognosis at this point would be significantly lower.