Endometrial cancer: When is adjuvant therapy necessary?

I had a hysterectomy due to endometrial cancer. My surgeon said my cancer was stage I and contained within the uterus. My abdominal fluid tested clear. Nevertheless, he recommends follow-up radiation therapy because the tumor had "minimally" invaded my cervix. But his recommendation conflicts with what I have read about the necessity of adjuvant therapy. Can you clarify?

- No name / No state given

Mayo Clinic oncologist Timothy Moynihan, M.D., and colleagues answer select questions from readers.

Answer

Endometrial cancer is highly curable with surgery alone if the cancer is confined to the lining of the uterus (endometrium). However, additional (adjuvant) therapy — such as radiation therapy or chemotherapy — may be recommended if the cancer has invaded the muscular wall (myometrium) of the uterus; has spread (metastasized) to involve nearby lymph nodes, blood vessels or the cervix; or if the tumor is high grade (G3 or G4).

Two types of radiation therapy are used to treat endometrial cancer:

External beam radiation therapy, which involves the use of high-dose X-rays
Internal radiation therapy (brachytherapy), which involves placing radioactive materials inside the body near the tumor

Brachytherapy causes significantly fewer side effects than external beam radiation therapy does. Adjuvant radiation therapy has been shown to decrease the risk of a local recurrence of endometrial cancer in the vagina. However, your oncologist can explain why a specific therapy is recommended for you.