Endometrial and Uterine Cancer: Same or Different?

Are endometrial and uterine cancer the same? Or are they different? If they are two different things, how can a person differentiate one cancer from the other?

We wondered about the above question when we were writing our earlier post on celebrities with endometrial cancer. After some hours of research, this is what we found out:

Endometrial cancer is a type of uterine cancer in the same way that avocado is a type of a fruit.

All endometrial cancer is a uterine cancer but not all uterine cancer is endometrial cancer. If we go with our avocado example, all avocados are fruits but not all fruits are avocados.

Uterine cancer can be used (and has been used) as a general term for endometrial cancer. In contrast you can’t use or substitute endometrial cancer for uterine cancer. This is so because there are other kinds of uterine cancer that do not affect the endometrium.

By way of illustration, here’s an image of a uterus (courtesy of fibroids.net) which should give us a clearer picture of the endometrial vs. uterine cancer riddle:

differences between endometrial vs uterine cancer

The innermost or inside lining is the endometrium. The middle layer is called the myometrium while the outermost layer is called the serosa or the perimetrium.

A little bit similar to our avocado example, huh?

differences between endometrial vs uterine cancer - avocado

But forget about the avocado, let’s focus on the uterus image above. Now, all cancer that start from the endometrium are called endometrial cancer. Meanwhile, cancers that originate in the myometrium (or the middle layer of the uterine wall) are called uterine leiomyosarcoma. Both endometrial cancer and uterine leiomyosarcoma can be generally called uterine cancer.

According to the Seattle Cancer Care Alliance, about 95% of uterine cancers are endometrial cancer. This means that only about 5% of uterine cancer are uterine leiomyosarcoma or the more rarer kinds of uterine cancer.

You want a more “medicalese” answer to the “Is endometrial cancer the same as uterine cancer” question? Here’s what Larry E. Puls, MD, Obstetrics & Gynecology, answered on behalf of Greenville Health System (via sharecare.com):

The answer is technically no.

Endometrial cancer does occur within the uterus, but it starts in the inside lining of the uterus, which is called the endometrium. The endometrium is the area that is responsible for a woman’s menstrual bleeding. It is very susceptible to the influence of the hormone estrogen. The ovaries primarily produce estrogen, but fat cells also produce estrogen. For this reason, with the significant rise in obesity in the US, endometrial cancer has become very common. In non-smoking women, endometrial cancer is the third most common cancer in the US!

Uterine cancer starts in the tissue that surrounds or supports the endometrium, the uterus. The uterus is largely made up of muscle, which is responsible for the contractions of labor. Some women unfortunately get cancers in that muscle. This is called a leiomyosarcoma. There are several varieties of sarcomas that occur in uterine supportive tissue; they act and spread differently from the more common endometrial cancers.

So there. We hope we helped clarify the endometrial vs. uterine cancer question for you!