Ovarian cancer is any cancerous growth that may occur
in different parts of the ovary. The majority of ovarian cancers arise from the epithelium (outer lining) of
the ovary. According to the American Cancer Society it is the 8th most common
cancer among women in the USA (excluding non-melanomaskin cancers). In the UK
ovarian cancer is the fifth most common cancer among females, after breast cancer, bowel
cancer, lung cancer and uterine cancer (cancer of
the uterus).
Approximately 5,500 women in the UK and 21,000 women in the
USA are diagnosed with ovarian cancer each year. Worldwide, around 140,000
women die of ovarian cancer every year.
Tragically, the overall five year survival rate is only 46
per cent in most developed countries (it is lower for more advanced stages).
However, according to the National Cancer Institute, if diagnosis is made
early, before the tumor has spread, the five year survival rate
is nearer 93 per cent. In 2009 scientists in the US said that current tests for
diagnosing ovarian cancer are not good enough .
Even modern screening tests for ovarian cancer, which
include a blood test for the CA 125 marker, combined with ultrasound, often result in
unnecessary surgery and "..are failing
to catch early signs of the disease..", a study at the University of
Alabama at Birmingham Comprehensive Cancer Center revealed.
What are the ovaries?
The ovary is the female gonad, while the testis is the male
gonad. A gonad is a reproductive gland that produces germ cells (gametes). A
male sperm is a gamete, and a female egg is also a gamete. Each human gamete
has 23 chromosomes, half the number of chromosomes contained in most types of
human body cells.
The ovary, also known as the egg sac, is one of a pair of
reproductive glands in women. The ovaries are located at either side of the
uterus (womb), in the pelvis. Each ovary is about the size and shape of an
almond. The ovaries produce ova (eggs) and female hormones, such as estrogen
and progesterone. These hormones regulate the menstrual cycle, pregnancy, and
control the development of female characteristics, such as body shape, body
hair, breasts, etc.
During the female menstrual cycle, which lasts about one
month, one egg is released from one of the two ovaries - the egg travels
through the fallopian tube and into the uterus. This is known as ovulation.
Cancer of the ovary can spread to other parts of the
reproductive system as well as surrounding areas, such as the stomach, vagina
and uterus. Ovarian cancer more commonly occurs in women aged 65 or over, but
can affect women of any age.
What is cancer?
Cancer is a class of diseases characterized by
out-of-control cell growth. There are over 100 different types of cancer that
occur in various parts of the body - each is classified by the type of cell
that is initially affected.
Usually our cells divide (multiply, form new ones) only when
old and dying ones need to be replaced. However, the controls that regulate
when a cell divides as well as when a cell should die sometimes become faulty.
This may result in cells not dying when they should, while additional cells are
still being added - an uncontrolled accumulation of cells. Eventually a mass of
cells is formed - a tumor.
Malignant and benign tumors
Tumors that stay in one place and demonstrate limited growth
are usually considered to be benign. Malignant, or more dangerous tumors emerge
when two things occur:
- Invasion - the cancerous cell manages to move throughout the body using the blood or lymph systems, destroying healthy tissue - this process is called invasion.
- Angiogenesis - the cancerous cells manage to divide and grow, making new blood vessels to feed themselves.
Metastasis
When a tumor manages to spread to other parts of the body
and grows, invading and destroying other healthy tissues, it is said to havemetastasized.
This process itself is called metastasis, and the result is a serious
condition that is extremely hard to treat.
Three main types of ovarian cancers (tumors)
Epithelial ovarian cancer is by far the most common form of
ovarian cancer. Germ cell and stromal ovarian cancers are much less common. Ovarian
cancer can also result from a cancer somewhere else in the body that has
spread:
- Epithelial ovarian cancer (epithelial ovarian tumors) - derived from cells on the surface of the ovary. It occurs mainly in adults.
- Germ cell ovarian cancer (germ cell ovarian tumors) - derived from the egg-producing cells within the body of the ovary. This rare type of cancer more commonly affects children and teenage girls.
- Stromal ovarian cancer (sex cord stromal tumors) - develops within the cells that hold the ovaries together.
- Cancers from other organs in the body can spread to the ovaries - metastatic cancers - a metastatic cancer is one that spreads from where it first arose as a primary tumor to other locations in the body.
What are the symptoms of ovarian cancer?
In the early stages, ovarian cancer usually has vague
symptoms which are not easy to recognize. In fact, doctors used to think that
ovarian cancer had no symptoms (unfortunately, many still do). Even though
healthcare professionals are much better at identifying ovarian cancer symptoms
these days, patients often attribute their symptoms to other conditions, such
as pre-menstrual syndrome, irritable bowel syndrome,
or a temporary bladder problem.
The main difference between ovarian cancer and other
possible disorders is the persistence and gradual worsening of symptoms. While
most digestive disorders have fluctuating symptoms, those of ovarian cancer are
more constant and steadily advancing.
The following are examples of possible early symptoms of
ovarian cancer:
- Pain in the pelvis
- Pain on the lower side of the body
- Pain in the lower stomach
- Back pain
- Indigestion or heartburn
- Feeling full rapidly when eating
- More frequent and urgent urination
- Pain during sexual intercourse
- Changes in bowel habits, such as constipation
As ovarian cancer progresses these symptoms are also
possible:
- Nausea
- Weight loss
- Breathlessness
- Fatigue (tiredness)
- Loss of appetite
Ovarian
cancer is not a silent killer. A study by the National Breast and Ovarian
Cancer Centre, Australia, found that 83% of women experience at least one
symptom of ovarian cancer in the year prior to their diagnosis. The researchers
also found that 17% of women waited more than three months after the onset of
their symptoms before visiting their doctor, with 8% waiting more than six
months. The most common symptoms, experienced by half of the study
participants, were abdominal symptoms such as fullness and pain. Bloating,
bowel or urinary symptoms were reported by approximately one third of
participants.
If you experience bloating, pressure or pain in the abdomen
or pelvis that persists for more than a few weeks you should see your doctor
immediately. If you have already been to the doctor and ovarian cancer was not
diagnosed, but treatment is not relieving symptoms, either see your doctor
again or get a second opinion. It is important that the evaluation includes a
pelvic examination.
People with close family members who have/had ovarian or
breast cancer should see a doctor who is trained to detect ovarian cancer.
What are the causes of ovarian cancer?
Although we know that ovarian cancer, like many other
cancers, is caused by cells dividing and multiplying in an unordered way,
nobody completely understands why cancer of the ovary occurs. We know that the
following risk factors are linked to a higher chance of developing the disease:
Family history
Most women who develop ovarian cancer do not have an
inherited gene mutation. Women with close relatives who have/had ovarian
cancer, as well as breast cancer, have a higher risk of developing ovarian
cancer compared to other women. There are two genes - BRCA1 and BRCA2 - which
significantly raise the risk. The BRCA1 and BRCA2 genes also raise the risk of
breast cancer. Those genes are inherited. The BRCA1 gene is estimated to
increase ovarian cancer risk by 35% to 70%, and the BRCA2 by 10% to 30%. People
of Ashkenazi Jewish descent are at particularly high risk of carrying these
types of gene mutations.
Women with close relatives who have/had colon cancer, prostate cancer or
uterine cancer are also at higher risk of ovarian cancer.
Genetic screening can determine whether somebody carries the
BRCA1 and/or BRCA2 genes. Although a test for gene mutations known to
significantly increase the risk of hereditary breast or ovarian cancer has been
available for more than a decade, a study by researchers from Massachusetts
General Hospital found that few women with
family histories of these cancers are even discussing genetic testing with
their physicians or other health care providers.
After
eight years of searching, an international team of scientists found that
a single nucleotide polymorphisms (SNP) on chromosome 9 that is uniquely linked
to ovarian cancer. The scientists estimated that women carrying that particular
version of the SNP on both copies of chromosome 9 have a 40 per cent higher
lifetime risk of developing ovarian cancer than women who do not carry it on
either copy of chromosome 9, while women with only one copy of the variant have
a 20 per cent higher lifetime risk of developing ovarian cancer than women who
have none.
In March 2013, scientists from the University of Cambridge
and the Institute of Cancer research announced that they had identified
over 80 genome regions that can increase a human's risk of developing ovarian,
breast and prostate cancers.
Age
The majority of ovarian cancers occur in women over 65 years
of age. A higher percentage of post-menopausal women develop ovarian cancer
compared to pre-menopausal women.
High number of total lifetime ovulations
There is a link between the total number of ovulations
during a woman's life and the risk of ovarian cancer. Four principal factors
influence the total:
- Never having been pregnant - women who have never become pregnant have a higher risk of developing ovarian cancer compared to women who have became pregnant. The more times a woman has become pregnant the lower her risk is.
- Never having taken the contraceptive pill - women who have never been on the contraceptive pill have a higher risk of developing ovarian cancer compared to women who have. Taking the Pill for 15 years halves the risk of ovarian cancer, a study by the Collaborative Group on Epidemiological Studies of Ovarian Cancer found.
- Early start of menstruation (early menarche) - women who started their periods at an early age have a higher risk of developing ovarian cancer.
- Late start of menopause - women whose menopause started
at a later age than average have a higher risk of developing ovarian cancer.
Scientists at the Centers for Disease Control and Prevention (CDC) found that survival among women with ovarian cancer is also influenced by age of menarche (when periods start) and total number of lifetime ovulatory cycles.
Some gynecologic surgeries may reduce the risk
Women who have had their fallopian tubes tied (tubal
ligation) are estimated to have a 67% lower risk of ovarian cancer. A
hysterectomy is said to reduce the risk by about one third.
Infertility or fertility treatment
Some studies have found a link between infertility treatment
and a higher risk of ovarian cancer. Nobody is yet sure whether the risk is
linked to infertility treatment, just infertility itself, or both. A Danish
study published in the peer-reviewed British Medical Journal concluded
that the use
of fertility drugs does not increase a woman's risk of developing ovarian
cancer. The study involved 54,362 women with infertility problems referred
to all Danish fertility clinics between 1963 and 1998.
Breast cancer
Women who have been diagnosed with breast cancer have a
higher risk of developing ovarian cancer.
HRT (Hormone replacement therapy)
HRT slightly
increases a women's risk of developing ovarian cancer. Experts say the risk
grows the longer the HRT continues, and returns to normal as soon as treatment
stops. Danish scientists reported that compared with women who have never taken
hormone therapy, those who currently
take it or who have taken it in the past are at increased risk of ovarian
cancer, regardless of the duration of use.
A UK study that was published in the peer-reviewed medical
journal The Lancet suggested that
between 1991 and 2005, an extra 1,000 women in the UK died of ovarian cancer
because they were on Hormone Replacement Therapy.
Foods high in acrylamide
A study in the Netherlands found a link between
acrylamide, a carcinogenic compound found in cooked, and especially burned,
carbohydrate rich foods, and increased risk of endometrial and ovarian cancer in
postmenopausal women.
Obesity/overweight
Being obese or overweight increases the risk of developing
many cancers. The more overweight you are, the higher the risk. Several studies
have also shown that obese cancer patients are more likely to have faster
advancing ones compared to cancer patients of normal weight. Obese older women
who have never used hormone replacement therapy have nearly twice the risk of
their normal weight peers of developing ovarian cancer, according to a
study by the researchers at the National Cancer Institute.
Endometriosis
Women who develop endometriosis have
an approximately 30% higher risk of developing ovarian cancer compared to other
women. Endometriosis is a condition in which cells that are normally found
inside the uterus (endometrial cells) are found growing outside of the uterus.
Danazol, a medication used to treat endometriosis has been linked to ovarian
cancer risk.
Shift work
Women
who work shifts are more likely to develop ovarian cancer than other females,
scientists from the Fred Hutchinson Cancer Research Center in Seattle, USA,
revealed in Occupational and Environmental Medicine.
In the same issue of the journal, other authors explained in
an Accompanying Commentary that "night-type people"
("owls") who work shifts are less likely to have a higher ovarian
cancer risk compared to "morning types" ("larks").
The authors wrote "We found evidence suggesting an
association between shift work and ovarian cancer. This observation should be
followed up in future studies incorporating detailed assessments of diurnal
preference (ie, chronotype) in addition to detailed data on shift
schedules."
Diagnosis of ovarian cancer
There is a tragic myth among many health care professionals
and patients in too many countries about early stage ovarian cancer having no
symptoms. A UK study, called The Target Ovarian Cancer Pathfinder study
which surveyed 400 UK general practitioners and over 1,000 women, including 132
with ovarian cancer, found that 80% of GPs in the UK
were wrongly of the view that women have no symptoms in the early stages of
ovarian cancer. Studies in countries with top healthcare services have come
up with similar findings.
The GP (general practitioner) will carry out a vaginal
examination and check for any visible abnormalities in the uterus or ovaries.
The doctor will also check the patient's medical history and family history.
Further tests will be ordered - these are usually done by a gynecologist - a
doctor who specializes in treating diseases of the female reproductive organs.
If the woman is diagnosed with ovarian cancer the doctor
will want to identify its stage and grade. The stage of a cancer
refers to the cancer's spread while the grade refers to how
aggressively it is spreading. By identifying the stage and grade of the cancer
the doctor will be able to decide on the best treatment. The stage and grade of
ovarian cancer alone cannot predict how it is going to develop.
The following tests are used to diagnose ovarian cancer:
- Blood test
There is a cancer marker called CA 125 (cancer antigen 125) which is made by certain cells in the body. A high blood level of CA 125 may indicate the presence of cancer, but could also be due to something else, such as infections of the lining of the abdomen and chest, menstruation, pregnancy, endometriosis, or liver disease. This blood test is just one test among others, designed to help the doctor make a diagnosis. Normal blood levels of CA125 alone do not definitely mean there is no cancer either. They are just indications.
- Ultrasound
This is a device that uses high frequency sound waves which create an image on a monitor of the ovaries and their surroundings. A transvaginal ultrasound device may be inserted into the vagina, while an external device may be placed next to the stomach. Ultrasound scans help doctors see the size and texture of the ovaries, as well as any cysts.
- Laparoscopy and possibly Endoscopy
A laparoscope - a thin viewing tube with a camera at the end - is inserted into the patient through a small incision in the lower abdomen. The doctor can examine the ovaries in detail, and can also take a biopsy (extract a small sample of tissue for examination). The patient will undergo a general anesthetic for this procedure. The doctor may carry out an endoscopy to determine whether the cancer has spread to the digestive system. - Colonoscopy
If the patient has had bleeding from the rectum, or constipation the doctor may order a colonoscopy to examine the large intestine (colon). The colonoscope - a thin tube with a camera at the end - will be inserted into the rectum. - Abdominal fluid aspiration
If the patient's abdomen is swollen the doctor may decide to carry out this test. A build up of fluid in the abdomen might indicate that the ovarian cancer has spread. A thin needle goes through the skin into the abdomen and a sample of the liquid is extracted. Some of the liquid may be drained into a bag if there is a lot of it (abdominal tap). The fluid is checked in the laboratory for cancer cells - Chest X-ray
This test will help the doctor see if the cancer has spread to the lungs, or to the pleural space surrounding the lungs.
- CT (computerized tomography) scan
X-rays are used to create a 3-dimensional picture of the target area.
- MRI (magnetic resonance imaging) scan
Magnets and radio waves produce 2-dimensional and 3-dimensional pictures of the target area.
Combined positron emission tomography (PET) and computed tomography (CT) scanning of patients in the early stages of ovarian cancer can enable physicians to determine whether the cancer has spread to nearby lymph nodes without having to perform surgery, reported scientists at San Gerardo Hospital, Monza, Italy.
Detecting ovarian cancer by testing cells from the uterus or
cervix
Pioneering biophotonics technology developed by researchers from Northwestern University and NorthShore University HealthSystem in Evanston, Illinois, can detect nanoscale changes in cervical and uterine cells that may indicate early stage ovarian cancer.
The scientists explained in the International Journal of Cancer (April 2013 issue) how by using PWS (partial wave spectroscopic) microscopy they were able to detect diagnostic changes in cells from the cervix and uterus taken from ovarian cancer patients via a minimally invasive procedure. These cells would look normal under an ordinary microscope.
The researchers believe their method could be in clinical use in about five years' time if it became commercialized.
Pioneering biophotonics technology developed by researchers from Northwestern University and NorthShore University HealthSystem in Evanston, Illinois, can detect nanoscale changes in cervical and uterine cells that may indicate early stage ovarian cancer.
The scientists explained in the International Journal of Cancer (April 2013 issue) how by using PWS (partial wave spectroscopic) microscopy they were able to detect diagnostic changes in cells from the cervix and uterus taken from ovarian cancer patients via a minimally invasive procedure. These cells would look normal under an ordinary microscope.
The researchers believe their method could be in clinical use in about five years' time if it became commercialized.
Using
dogs to "sniff out" ovarian cancer
Researchers at the University of Pennsylvania explained that by utilizing the acute sense of smell in detection dogs, alongside chemical and nanotechnology methods, they hope to create a more comprehensive system for screening for ovarian cancer.
Researchers at the University of Pennsylvania explained that by utilizing the acute sense of smell in detection dogs, alongside chemical and nanotechnology methods, they hope to create a more comprehensive system for screening for ovarian cancer.
The 4 stages of ovarian cancer
Ovarian cancer is classified into four stages, with stage 4
being the most advanced.
- Stage 1 - the cancer is confined to one or both ovaries. This is subdivided into three groups:
- Stage 1a - the cancer is confined to just one ovary (contained inside it).
- Stage 1b - the cancer is confined to both ovaries (contained inside them).
- Stage 1c - either 1a or 1b, but there is come cancer on the
surface of one or both ovaries, or cancer cells are found in fluid extracted
from inside the abdomen during surgery, or the ovary bursts during or before
surgery.
- Stage 2 - the cancer has spread to the uterus,
fallopian tubes or some other areas in the pelvis (tummy area). This is
subdivided into 3 groups:
- 2a - the cancer has spread into the uterus (womb) or the fallopian tubes.
- 2b - the cancer has spread into other tissues in the pelvis, such as the rectum or bladder.
- 2c - 2a and 2b, and there is cancer on the surface of one or
both ovaries, or cancer cells are identified in fluid extracted from inside the
abdomen during surgery, or the ovary bursts during or before surgery.
- Stage 3 - the cancer has spread into the peritoneum
(the lining of the abdomen), or to the lymph nodes in the upper abdomen, groin
or behind the uterus. Most ovarian cancers are diagnosed at this stage. This
stage is divided into three subgroups:
- 3a - an examination with a microscope of tissue taken from the peritoneum (lining of the abdomen) or the omentum (fatty layer over the top of the intestines) detects cancer cells.
- 3b - tumor growths are identified in the peritoneum 2cm or smaller.
- 3c - tumor growths larger than 2cm are identified in the
peritoneum. Cancer is found in the lymph nodes in the groin, behind the womb or
the upper abdomen.
- Stage 4 - the cancer has spread beyond the abdomen to other parts of the body, including such organs as the lungs or the liver. If cancer is just found on the surface of the liver, but not inside it, it is still stage 3.
Treatment for ovarian cancer consists of surgery, chemotherapy, a combination of surgery with chemotherapy, and sometimes radiotherapy. The kind of treatment depends on many factors, including the type of ovarian cancer, its stage and grade, as well as the general health of the patient.
Some studies have indicated that specialized hospitals tend
to have better survival rates for ovarian cancer patients, compared to general
hospitals. Dutch
ovarian cancer patients who were treated at a semispecialized or specialized
hospital survived longer than those treated at a general hospital, reported
researchers at the University Medical Center Utrecht in The Netherlands.
Surgery
The surgical removal of the cancer is performed in the vast
majority of ovarian cancer cases, and is often the first treatment the patient
will undergo.
Unless the ovarian cancer is very low grade, the patient will require an extensive operation that includes the removal of both ovaries, the fallopian tubes, the uterus, nearby lymph nodes, and the omentum (a fold of fatty abdominal tissue). Cancer often spreads into the omentum. In most cases the operation will be carried out by a gynecologic oncologist surgeon - a specialist in surgery for women with cancer of the reproductive organs. This operation, sometimes referred to as a total hysterectomy, will mean that the woman will begin her menopause immediately. Recent research by Canadian scientists found that premature removal of the ovaries increases the risk of lung cancer.
If the cancer is confined to just one of the ovaries the surgeon may just remove the affected ovary and the adjoining fallopian tube. The woman will have a chance of being able to conceive. If both ovaries are removed it will not be possible to conceive.
Surgery for ovarian cancer will require a hospital stay of
up to two weeks, plus a recovery period of at least six weeks when the patient
gets back home.
Chemotherapy
Chemotherapy is the use of chemicals (medication) to treat
any disease - more specifically in this text, it refers to the destruction of
cancer cells. Cytotoxic medication prevents cancer cells from dividing and
growing. When health care professionals talk about chemotherapy today, they
generally tend to refer more to cytotoxic medication than others. Chemotherapy
for ovarian cancer, as well as most other cancers, is used to target cancer
cells that surgery cannot or did not remove.
Patients will typically receive a combination of carboplatin (Paraplatin) and paclitaxel (Taxol) intravenously (injected into the bloodstream). As it is injected into the bloodstream it can target cancer cells in the reproductive system, as well as any cancer cells that may have reached elsewhere in the body.
Treatment usually involves 6 to 12 chemotherapy sessions
which will be given three to four weeks apart so that the body has time to
recover. One session usually consists of a 3-hour gradual injection of the
medicine into the body; sometimes it may be extended to 24 hours. Extended
injections require an overnight stay in hospital.
Compounds
in cranberries may help improve the effectiveness of platinum drugs that are
used in chemotherapy to fight ovarian cancer, scientists at Rutgers
University found.
Monitoring response to chemotherapy
Tests will be carried out to determine how well the
chemotherapy is working. This will include blood tests to see if levels of
CA125 have dropped, and imaging scans to see if tumors have shrunk. Sometimes
the surgeon may want to have another look inside.
The patient will be in remission if all tests are
clear of cancer. In remission means the cancer is under control.
If cancer is still present after chemotherapy treatment
doctors will switch to other treatments. Patients who did not respond well to a
specific type of chemotherapy treatment are unlikely to respond well if the
same treatment is done again. This may involve another type of chemotherapy,
such as intraperitoneal chemotherapy, in which the medication is aimed at the
stomach, or radiotherapy.
Researchers in the Duke Comprehensive Cancer Center reported
that the addition of a chemotherapeutic drug for leukemia - dasatinib (Sprycel) -
to a standard regimen of two other chemotherapy drugs appears to enhance the
response of certain ovarian cancers to treatment, according to a pre-clinical
study. Study leader, Deanna Teoh, M.D. said "These findings
indicate that we may be able to direct the use of a targeted therapy like
dasatinib based on gene expression pathways in select ovarian cancers."
Side effects of chemotherapy
Chemotherapy targets rapidly dividing cells. Unfortunately,
healthy rapidly dividing cells, such as red and white blood cells and hair
follicles may also be affected. The severity and types of side effects depend
on the type of medication, number of treatments, and some aspects of the
patient and their general health. This may result in the following side
effects:
- Nausea, vomiting - medication for this may be given intravenously during chemotherapy sessions.
- Diarrhea.
- Hair loss.
- Loss of appetite.
- Mouth sores.
- Anemia.
- Infections because the white blood cell count is low (leucopenia).
In the vast majority of cases the damaged healthy cells
repair themselves rapidly after treatment is over and the side-effects will
soon disappear.
Radiotherapy
Radiation is not the mainstay of ovarian cancer treatment -
it is not generally considered effective for ovarian cancer. It may be used if
there are small traces of cancer in the reproductive system, or to treat the
symptoms of advanced cancer. External radiotherapy may be used to clear traces
of cancer left after chemotherapy, while internal radiotherapy may be used for
advanced cancer. Radiotherapy may cause the following symptoms; some symptoms
may not appear until a long time after treatment is over:
- Bladder infections
- Diarrhea
- Constipation
- Irritation, darkening of your skin that the radiation beams hit
- Nausea
- Frequent urination
- Abdominal pain
Source:http://www.medicalnewstoday.com/articles/159675.php