As a part of my efforts to become the most effective cancer advocate that I can, I have challenged myself to expand my working knowledge of cancer beyond just breast cancer. Using the assorted cancer awareness month observations as my guide, I have been using my blog to share what I’ve been learning about a number of different types of cancer. I have already dedicated posts to Childhood Cancer Awareness Month and Blood Cancer Awareness Month, and I’m planning to dedicate posts to Thyroid and Prostate Cancer Awareness Months as well. Today, though, I am going to focus on ovarian and other gynecological cancers in honor of Ovarian Cancer Awareness Month as well as the more broad Gynecologic Cancer Awareness Month. With more than 80,000 women expected to be diagnosed with a gynecological cancer in this calendar year, I think this awareness month is one that all women need!
Gynecologic Cancer Awareness Month was first established back in 1999 by the Foundation for Women’s Cancer. The goal of this month, which is marked every September, is to increase awareness of these cancers in order to enable earlier detection, better treatment, and a greater chance of recovery for individuals diagnosed with a gynecologic cancer. With the exception of cervical cancer, there are no established, reliable screening tests for any of these gynecologic cancers. Moreover, the symptoms associated with these types of cancer overlap significantly with other common infections and diseases, including urinary and bladder infections, common STDs, kidney stones, and even PMS. Because of this, gynecological cancers are often diagnosed at a more advanced stage, making it much more difficult to treat these cancers. Therefore, it is critically important that all women are familiar with what is normal for their own bodies and are knowledgeable about the range of cancers that can occur in the female reproductive system. To that end, I am going to use this post to give a brief overview of each of the five primary gynecological cancers (ovarian, uterine, cervical, vaginal, and vulvar cancers), some important stats for each, and a list of links where you can find additional information. Even if you are familiar with these cancers, it can’t hurt to review this information again!
As you might have intuited, ovarian cancer is any cancer that develops from the cells within the ovary. There are three general cell types that make up the ovary: epithelial cells (which make up the general structure of the ovary), germ cells (which give rise to the eggs), and stromal cells (the cells that produce the female hormones estrogen and progesterone). Each of these cell types can develop into one of three corresponding ovarian cancer subtypes. The most common subtype of ovarian cancer is epithelial ovarian cancer, which accounts for 90% of all ovarian cancers. Germ cell and stromal cancers are both significantly more rare, accounting for less than 2% and approximately 1% of ovarian cancers, respectively. There is no recommended screening test for ovarian cancer and the symptoms associated with ovarian cancers can be especially hard to discern from those associated with more common gynecological and renal disorders, making ovarian cancer very difficult to diagnose. As a result, while ovarian cancer accounts for just 3% of all cancer in women, it is the fifth leading cause of cancer death.
While the cause of most ovarian cancers remains unknown, a number of risk factors for the disease have been identified. In general, it appears that the more ovulations that a woman experiences over the course of her lifetime, the higher her personal risk for developing ovarian cancer, likely due to increased exposure to estrogen. Therefore, a history of taking fertility drugs or estrogen therapy is considered a risk factor for ovarian cancer. The flip side of that coin, though, is that anything that reduces the number of lifetime ovulations a woman experiences can lower her risk. This includes having multiple pregnancies, breast feeding, taking birth control pills, or having a tubal ligation. Women who are obese are also at increased risk for ovarian cancer because fat cells are capable of converting certain other hormones into estrogen. A family or personal history of ovarian, breast, uterine or colorectal cancer is also a risk factor for ovarian cancer because the genes that predispose individuals to those cancers (including BRCA1 and BRCA2) are often associated with an increased sensitivity to estrogen. As with breast cancer, older women are at an increased risk of ovarian cancer, as are women who have a history of smoking and/or alcohol use. However, while each of these risk factors may increase risk of ovarian cancer, having these factors does not guarantee that an individual will develop the disease, just as the absence of these risk factors does not guarantee that a woman will not develop cancer.
In terms of the numbers, it is estimated that 22,280 women will be diagnosed with ovarian cancer in 2012 and 15,500 women will die of the disease in that same time period. One out of every 72 women will be diagnosed with ovarian cancer in their lifetimes. The 5-year survival rate for ovarian cancer is just 43.7%. In the US, we spend approximately $4.4 billion treating ovarian cancer every year.
The National Cancer Institute (my primary source for this information, along with the American Cancer Society) allocated 2.2% (or $112.3 million) of its budget in 2010 for ovarian cancer research.
The information in this section was provided to the public courtesy of the NCI and the American Cancer Society. The ovarian cancer homepage of the NCI can be found here and the ACS ovarian cancer section can be found here. All of the statistics came from the Surveillance Epidemiology and End Results (SEER) fact sheets on ovarian cancer, here.
Uterine cancer, as follows logic, is cancer that develops in the tissues that make up the uterus. There are two primary layers of the uterus that each give rise to a corresponding subtype of uterine cancer:
- The inner layer (or lining) or the uterus is called the endometrium. This is layer that thickens and grows each month in preparation for gestation. Cancers of this layer account for 98% of all uterine cancers and are known as endometrial cancer.
- The outer layer of the uterus is made of muscle tissue and is known as the myometrium. Cancers of this soft tissue are known as uterine sarcomas and are very rare.
- The use of estrogen therapy to treat menopause without a concomitant use of progesterone.
- Being obese.
- Taking tamoxifen. Tamoxifen acts as an anti-estrogen in breast tissue, but acts as a pro-estrogen in the uterus.
- A history of certain subtypes of ovarian tumors that are capable of producing estrogens.
- Poly-cystic ovary syndrome (PCOS)
- A high lifetime number of menstrual cycles, due to early puberty, late menopause, never being pregnant/breast feeding, or some combination thereof.
- Uterine stromal sarcomas, which develop in the supporting connective tissues (or stroma) of the uterus and account for less than 1% of uterine cancers. Stromal sarcomas are generally low grade (not very abnormal, slow growing) and the prognosis for this type of cancer is generally good.
- Uterine leiomyosarcomas (LMS), which develop in the muscle cells of the uterus and account for approximately 2% of uterine cancers.
The information in this section was also provided to the public courtesy of the NCI and the American Cancer Society. The endometrial cancer homepage of the NCI can be found here and the uterine sarcoma homepage of the the NCI can be found here. The ACS endometrial cancer section can be found here and the ACS uterine sarcoma section can be found here. All of the statistics came from the Surveillance Epidemiology and End Results (SEER) fact sheets on uterine cancer, here.
Cervical cancer is any cancer that develops from the tissues of the cervix, which is the organ that connects the uterus and the vagina. There are two primary subtypes of cervical cancer:
- Squamous cell carcinoma, which develops from the outer layer of the cervix (or exocervix) and accounts for 80-90% of all cervical cancers.
- Adenocarcinoma, which develops from the mucus-producing gland cells that line the inside of the cervix (which is also known as the endocervix).
Cervical cancer is generally slow growing and unlike the other gynecologic cancers that I’ve covered thus far in this post, can be detected even in the pre-cancerous stages of the disease with regular pap tests. In addition, we also know that virtually all cervical cancers are caused by infection with the human papilloma virus (HPV), making cervical cancer one of the only cancers with both a known cause AND a reliable screening test. As a result, while cervical cancer used to be one of the leading causes of cancer death in women, the mortality rate of cervical cancer has declined by over 70% since 1955.
While cervical cancer is generally pretty rare, infection with HPV is not. In fact, over 50% of all sexually active people have been infected with HPV at some point in their lives, making HPV the most common sexually transmitted infection in the United States. While we often talk about HPV as if it is a single virus, the reality is that there are actually more than 150 genetically unique but highly related HPVs, more than 40 of which are capable of being spread via skin-to-skin contact. These viruses can be divided into two primary categories of HPVs: low risk HPVs that do not cause cancer and are primarily associated with genital/skin warts and high risk HPVs that are known to cause cancer. There have been at least 12 high risk HPVs identified to date. Infection with a high risk HPV accounts for approximately 5% of all cancers worldwide, including virtually all cervical cancer (as I noted above), 85% of anal cancers, and more than half of all vaginal, vulvar, penile, and oropharyngeal cancers. There are currently two FDA-approved vaccines targeted at preventing high risk HPV prevention. Safe sex practices are also important and effective for preventing HPV infection of any kind.
It is important to note that most high risk HPV infections have no symptoms and go away on their own with no medical treatment. However, occasionally, the body is unable to clear the infection on its own, resulting in a chronic HPV infection. Chronic HPV infection can result in cellular changes and abnormalities that, if left to grow and reproduce unchecked over a long period of time, can result in cancer. This process can take as long as 10-12 years after the initial HPV infection, resulting in a lengthy “pre-cancerous” phase. Fortunately, regular pap tests, in which the doctor scrapes cells from the cervix and examines them under the microscope for cellular abnormalities, can detect the majority of pre-cancerous cervical changes that can then be treated well before they ever develop into full blown cervical cancer. A pap test that is positive for abnormal cervical cells coupled with a positive test for HPV is very effective at identifying both cervical cancer and pre-cancerous cervical cells. As a result, the American Cancer Society currently recommends the following cervical cancer screening guidelines, even for those who have been vaccinated against HPV:
- For women aged 21 to 29: Pap test every three years. No HPV screen.
- For women aged 30 to 65: HPV test every five years or pap test every three years.
- For women over the age of 65, regular screening can be stopped unless the individual has a history of abnormal pap tests and/or detection of precancerous cervical cells.
In terms of statistics, it is estimated that 12,170 women will be diagnosed with cervical cancer in 2012 and 4, 220 women will die from the disease. One out of every 147 women will be diagnosed with cervical cancer in their lifetimes, a number that has been markedly reduced over the past few decades due to the development and improvement of pap tests and behavioral modifications to prevent HPV transmission. The US spends $1.4 billion treating cervical cancer every year.
The NCI allocated $76.5 million (or 1.5%) of it’s annual in 2010 for cervical research, with large portions of that research focused on better understanding how HPV causes cancer and the detection and treatment of pre-cancerous cervical cell changes.
The information in this section was also provided to the public courtesy of the NCI and the American Cancer Society. The cervical cancer homepage of the NCI can be found here and the ACS cervical cancer section can be found here. I also found this overview of HPV and cancer from the NCI to be particularly informative. All of the statistics came from the Surveillance Epidemiology and End Results (SEER) fact sheets on cervical cancer, here.
Vaginal and Vulvar Cancer
Because there are a lot of similarities between vaginal and vulvar cancers and because both of these cancer types are fairly rare (together, they only account for 6 – 7% of all gynecologic cancers), I’m going to tackle these two cancers together. Vaginal cancers are, as you would imagine, any cancer that forms in the tissues of the vagina. Vulvar cancers are any cancer that develops in the tissues of the vulva (the external female genital organs including the clitoris, the vaginal lips, and the opening to the vagina itself). There are four major subtypes of both vaginal and vulvar cancers:
- Squamous cell carcinomas, which develop from the epithelial cells of both organs and are the most common subtype of both vaginal and vulvar cancers. In both organs, squamous cell carcinomas are generally slow to develop and include a long pre-cancerous phase as in cervical cancer. In the vagina, these pre-cancerous changes are known as “vaginal intra-epithelial neoplasia” or VAIN and in the vulva, these changes are known as “vulvar intra-epithelial neoplasia” or VIN. The stage of VAIN/VIN is used to describe the extent of cellular abnormalities present, with Stage I VAIN/VIN being the least abnormal and Stage III VAIN/VIN being the most abnormal.VAIN/VIN can be detected using a pap test, as in cervical cancer.
- Adenocarcinomas, which develop in the glandular cells of the vagina or vulva. Adenocarcinomas account for 15% of vaginal cancers and 8% of vulvar cancers. In the vulva, adenocarcinomas generally arise in the Bartholin glands, which are located just inside the vaginal opening or in the sweat glands of the skin.
- Melanoma, which develops from the pigment-producing cells of the vagina or vulva. Melanomas account for 9% of vaginal cancer and 6% of vulvar cancer. Melanomas are generally more aggressive than squamous cell carcinomas or adenocarcinomas. Basal cell carcinomas, a common but less aggressive type of skin cancer can also occur on the vulva, although they are very rare.
- Sarcomas, which develop in the soft structural tissues of the vagina or vulva. Sarcomas account for 4% of vaginal cancers and less than 2% of vulvar cancers.
Approximately half of all vaginal and vulvar cancers are caused by HPV infections and as with cervical cancer, these cancers can often be detected via pap test in the pre-cancerous stage. The risk factors for both vaginal and vulvar cancer are highly similar and include HPV or HIV infection, a personal history of other gynecological cancers, and a history of smoking and/or drinking alcohol. The risk of developing either of the cancers increases with age, with over 50% of all vaginal and vulvar cancers occurring in women over the age of 70. Other risk factors for vaginal cancer include exposure in utero to diethylstilbestrol (DES, a hormonal drug given between 1940 and 1971 to prevent miscarriage) and vaginal adenosis (a condition that affects 40% of all women where there are hormonal glands present within the vagina). Other risk factors for vulvar cancer include Lichen Sclerosis (a disorder that causes the vulvar skin to become very thin and itchy) and a family or personal history of melanoma/atypical moles.
It is estimated that 2,680 women will be diagnosed with vaginal cancer in 2012 and 840 women will die from the disease. During that same time period, it is estimated that 4,490 women will be diagnosed with vulvar cancer and 950 women will die from the disease. One out of every 368 women will be diagnosed with vulvar cancer at some point in her lifetime. The equivalent statistic for vaginal cancer was not available. Details about the annual cost of treating these cancers in the United States and the NCI research budget for these cancers was not available.
The information in this section was also provided to the public courtesy of the NCI and the American Cancer Society. The vaginal cancer homepage of the NCI can be found here and the ACS vaginal cancer section can be found here. The vulvar cancer homepage of the NCI can be found here and the ACS vulvar cancer section can be found here. The statistics on vulvar cancer came from the Surveillance Epidemiology and End Results (SEER) fact sheets on vulvar cancer, here. The equivalent statistics from SEER were not available for vaginal cancer.
If you would like to learn more about gynecological cancers in general, or one of these types of cancers in particular, I highly recommend reading through the NCI’s web pages dedicated to ovarian, uterine/endometrial, cervical, vaginal, and vulvar cancers. The “snap shot” reports linked to in each subsection are particularly informative, especially the sections discussing recent research investments and findings. I also highly recommend the CDC’s section on gynecologic cancers, especially the Inside Knowledge fact sheets.
The American Cancer Society also has the following subsections of their “Learn About Cancer” webpage dedicated to gynecologic cancers:
The American Association for Cancer Research also recommends the following cancer advocacy and patient support organizations for each type of gynecological cancer that I’ve covered here:
- Facing Our Risk of Cancer Empowered (or FORCE; for women with a high risk of developing breast or ovarian cancer)
- Foundation for Women’s Cancer
- Gynecologic Cancer Foundation
- National Ovarian Cancer Coalition
- Ovarian Cancer National Alliance
- The Ovarian Cancer Research Fund
- National Cervical Cancer Coalition
Note: While I am a biomedical scientist, I am not considered an expert (medical or otherwise) on any of these types of cancer. This post, as with future planned “awareness month” posts, is not meant to be an in depth review of these types of cancer. Rather, I only wanted to provide a brief overview of each type of cancer in the gynecological cancer family in order to help further the larger cancer community’s awareness of each of these cancers. Moreover, while I provided links to a number of gynecological cancer organizations at the end of this post, I have not researched these organizations to the extent that I do for my “Spotlight On” series of posts. Until I can research them further, I am not explicitly advocating financial donations to these organizations (although I certainly won’t advise you against it either should you find them worthy!). Instead, I am recommending them here because each organization is a well respected leader in these specific areas and is considered a reputable source for further information on gynecological cancers.