Benign Tumors - Benign tumors are, by definition, not malignant (not cancerous). Though they can still create problems by pressing on surrounding tissue, it is rare that one would be life-threatening. An example of a common benign tumor is the uterine fibroid . Benign tumors can develop in any of the female reproductive organs.

Tumors of Low Malignant Potential - This is a class of ovarian tumors that are, as the name implies, not likely to invade and spread. They are more common in younger patients, and are also called borderline tumors.

Malignant Tumors (Cancer) - The female reproductive system contains perhaps a greater variety of malignant tumors than any other in the human body. Here are the main types:

Carcinomas, the most common category of gyn cancer, come from epithelial cells. Epithelial tissue provides the linings and coverings in our body. Common types of gyn carcinomas are:

- Squamous Cell Carcinoma - Squamous cells are flat cells that are mostly found on surfaces that are in contact with the outside environment, and their job is to protect the body from environmental dangers. Accordingly, the cancer trigger for squamous cell tumors is often an environmental one - sunlight, tobacco, and HPV are three of the most common factors in promoting squamous cell carcinomas. This type of cancer is the most common one in the vulva, vagina, and cervix. Squamous cell cancer is generally slow to develop and grow, and often responds well to cancer therapies.

- Adenocarcinoma - The prefix "adeno" refers to glandular cells. Adenocarcinomas occur in tissues that excrete some substance. Most endometrial and ovarian cancers are adenocarcinomas, and some cervical and vaginal cancers as well. Ovarian and endometrial glandular tissues excrete hormones, and these cancers seem to be influenced by hormones as well, although the mechanisms are not clearly understood at this point.

Most subtypes of carcinomas and adenocarcinoma are named for the specific types of cells from which they develop(e.g. serous adenocarcinomas develop in serous cells, which excrete a thin liquid called a serum) or the way they look (e.g. endometrioid adenocarcinomas and clear cell carcinomas). In general, the differences in these tumor types aren't significant in terms of cancer prognosis or treatment (the organ affected is more important in this regard). There are a few exceptions, and among them is:

- Malignant Melanoma - an aggressive type of carcinoma that can affect the vulva and vagina. This tumor begins in the melanocyte, a type of cell in the skin and mucous membranes of the body that produces pigment (melanin).

Sarcomas - Sarcomas develop in bone, muscle, and connective tissue. 5% of uterine cancers and 2-3% of vaginal and vulvar cancers are sarcomas. Sarcomas generally carry a less favorable prognosis than carcinomas.

Germ Cell Tumors - Germ cells in females are the eggs (ova). In Western countries, about 5% of ovarian cancers are germ cell cancers, although a much higher percentage of benign ovarian tumors are of germ cell origin. In Asia, 15% of ovarian cancer is germ cell cancer, but this is partly because the epithelial ovarian cancers are less common there.

Sex Cord-Stroma cells in the ovary, including granulosa cells and theca cells, make up the tissues that generate the follicle for the ovum released each month, and they also can become cancerous. These tumors make up about 5% of ovarian cancers, and are more often discovered in Stage 1 than ovarian cancers in general. Granulosa cells release estrogen, and granulosa tumors release too much estrogen. This can cause its own problems, such as endometrial hyperplasia, which in turn can cause abnormal bleeding. 5% of the time, this tumor occurs in pre-pubescent girls, and the first sign can be early onset of puberty due to over-production of estrogen.

Gestational trophoblastic disease - Sometimes very early in pregnancy, after the blastocyst (pre-embryo) implants in the uterus, something goes amiss. The embryo fails to develop, but the cells that are forming the placenta continue to grow, and can become malignant.

Mixed tumors - some tumors are of more than one type. For example "mixed mullerian tumors" of the uterus are also called carcinosarcomas to show that they are derived both from epithelial and connective tissues.

There are many cancer subtypes not specifically mentioned here. Ovarian cancer alone has at least 30 subtypes.