New evidence adds strength to arguments that doctors should be extremely cautious about using a procedure performed on about 50,000 women a year during surgery to remove the uterus because of the risk that it may spread cancer.

The procedure, power morcellation, uses a device to cut uterine tissue into pieces before removal through small incisions made during minimally invasive surgery. It is also used to remove fibroid tumors.

Recent reports indicate that some women have been harmed when the device, a morcellator, sliced into tumors they and their doctors did not know existed and spread cancer cells through the abdomen.

Now, a new study, published Tuesday in The Journal of the American Medical Association, found that undetected tumors in women having hysterectomies are more common than many experts had thought, a conclusion that is likely to fuel calls to limit or eliminate the procedure.