How successful are pap smears in detecting cervical and uterine cancers?
George Nicholas Papanicolaou established the Pap smear in the 18th century when he became intrigued by the guinea pigs vaginal smears as he was studying them. He quickly began to start his research on the female reproductive system, most specifically the different cytology slides he could obtain. His stake in the field was his book published in 1943, “Diagnosis of Uterine Cancer by Vaginal Smear.” It covered topics like physiological changes of a menstrual cycle, the hormones incorporated, and vaginal smears that led to his classifications of disease and malignancies. This jump started the
screening for cervical cancer
and can attest to a significant decline in
cases of cervical cancer
. Later, he published another book specific to just distinguishing between healthy and diseased tissue throughout the entire body. These two publications were just two of the four he finished in his life on top of awards and honorary degrees. (Tan, 2015)
Papanicolaou was certainly a
huge help in the advancement of cytology reporting. Since then, we have been
able to learn and understand more about pap smears, cervical cancer and the
role pap smears plays in diagnosing them. Although both cancers begin in the
same area, the uterus; we can differentiate them by their pathophysiology’s.
The question really stands, how successful are pap smears in detecting these
cancers? This can be argued on a few bases, but sticking to the facts we can
find out how successful they are, how they can be preventive, and what to
expect if a woman does find herself diagnosed. Several factors can be taken
into account such as the pathogenesis, level of disease, the manifestations,
precipitating factors, and several more. Uterine and Cervical cancers both come
with their own etiologies, epidemiology’s and prognosis.
There are a few different
ways to screen for cervical cancer, and this will look directly into the Pap
smear procedure. The Pap smear allows for a better look into the cells in the
cervix, the opening of the uterus. The test is looking for cancerous and
abnormal cells that could lead to cancerous outcomes. In the test an
obstetrician- gynecologist will scrape away a portion of cervix cells. The use
of a speculum helps the doctor keep the walls of the cervix open to have a
clear view and retrieve a good sample. The specimen will then be tested in a
controlled laboratory setting where a technician will observe for
abnormalities. An official cytology report will be sent to the doctor and then
given back to the patient for further counsel if needed. Results will be
abnormal or negative (normal). Several sources believe the Pap smear to be very
accurate in the screening of cervical cancer. It also is a very preventive
measure to take, as long as the patient is compliant with the doctor’s
guidelines. By detecting cervical cancer early, treatment can begin to decrease
the risk of spreading and growth of the tumors. Pap smears have been estimated
to reduce cervical cancer rates and mortality by 80%. (Weber, 2017) In
comparison, up to 80% of women diagnosed with invasive cervical cancer have not
received a pap smear in the past 5 years. (Stöppler)
CIN or, cervical
intraepithelial neoplasia is a precancerous condition of abnormal cell growth
on the cervix. Intraepithelial means that the abnormal cells are growing on the
surface or the epithelial tissue of the cervix. Neoplasia is referring to the
growth of new cells. Signs and symptoms can be obvious but can also resemble
several conditions that females could encounter. These symptoms can include
abnormal vaginal bleeding, bleeding after sexual intercourse, pelvic pain,
discharge, and pain during sexual intercourse. (Stöppler) It is recommended
that women start getting pap smears at the age or 21. This is most important if
you are HIV positive or have a weakened immune system. (Weber, 2017)
These screenings should continue from ages 21 to 29 with cytology alone
every 3 years. From ages 30-65, women should continue cytology screening every
three years and add HPV testing. After 65 no screening is necessary as long
past screenings are normal and no high risk is present. (Boardman, 2018)
Over the years professionals
have found it difficult to all be on the same page about reporting. Some levels
of abnormal results can include atypia, mild, moderate, severe dysplasia, and
carcinoma in situ. The creation of the Bethesda System has given one reporting
system for all health care professionals. In 1988 the National Cancer Institute
held a conference for the creation of this system, it was then re-evaluated in
2001. There are four major classifications that make it easier for this
universal system to work. “ASC-US: This abbreviation stands for atypical
squamous cells of undetermined significance. LSIL: This abbreviation stands for
low-grade squamous intraepithelial lesion. Under the old system of
classification, this category was called CIN grade I. HSIL: This abbreviation
stands for high-grade squamous intraepithelial lesion. Under the old system of
classification, this category was called CIN grade II, CIN grade III, or CIS.
ASC-H: This means atypical cells are present and HSIL cannot be excluded.”
CIN cases are most always
caused by infection with oncogenic types of HPV or, Human Papillomavirus.
There are 12 known types of high risk HPV, which are the most prevalent
associations with cervical cancer. Cervical cancer results from a genital
infection with HPV, a known human carcinogen. Because most HPV infections are
transient or, passing in and out of existence in a patient, it causes only
temporary changes in cervical cells. (National Cancer Institute, 2014)
About 90% of HPV infections clear on their own within months to years
with no sequelae. (Boardman, 2108) This makes it difficult to catch the HPV
infection and in turn cervical cancer. Too frequent of screenings might be
problematic for several reasons. One being that treating these abnormalities
thinking it was HPV but that went away anyways would cause unnecessary stress
on the patient. Also, putting strain on the cervix several times in any period
of time can weaken the tissue and could ultimately affect the woman’s fertility.
Interestingly enough, it can take up to 20 years for a persistent infection
with a high risk HPV to become cancerous. (National Cancer Institute, 2014) Low
risk HPV infections rarely or almost never cause cervical cancer. (Boardman,
2018) However if lesions are found and not treated, they are more than likely
to turn into cervical cancer. (National Cancer Institute, 2014)
There are different levels
of cervical cancer that decipher the progression on epithelial tissue. CIN
grade 1 is low grade neoplasia involves around one-third of the thickness of
the epithelium. CIN 2 refers to the abnormal changes in about one to two-thirds
of the layer. CIN 3 is the most severe affecting over two-thirds of the
epithelium. 5% of HPV infected patients will acquire CIN grade 2 or 3 lesions
with three years of infection. Only 20% of CIN 3 lesions progress to invasive
cervical cancer within 5 years. Only 40% of CIN 3 lesions progress to invasive
cervical cancer within 30 years.
Genetics can also play a role in a woman’s development of cervical cancer; genetic connection holds fewer than only 1% of cervical cancers. “Women who have an affected first degree biological relative have a two fold relative risk of developing a cervical tumor compared with women who have a nonbiologic first degree relative with a cervical tumor.” Some specific genetic factors have been shown to be in association. The tumor necrosis factor is involved with cell apoptosis and a high incidence of cervical cancer. Polymorphisms, another gene dealing with apoptosis, have been linked to the increased rate of HPV and in turn, cervical cancer.
Cervical cancer is the leading cause of cancer related morbidity in developing countries, but is very uncommon in the United States. “Since 2004 rates have decreased by 2.1% per year in women younger than 50 years and by 3.1 per year in women 50 years of age and older. ACS reports 12,170 new cases of cervical cancer would be diagnosed in 2012.” Age related demographics from 2004-2006 were highest among women from 50-79. But cervical cancer is possible to be present in any sexually active woman. In terms of race, cervical cancer rates per 100,000 women in the US from 2005-2009 are across the board: Hispanic 11.8, African American 9.8, American Indian/ Alaska Native 8.1, White 8.0 and Asian/ Pacific Islander 7.2. Internationally, 500,000 women are diagnosed every year.
Prognosis for cervical
cancer is very good, especially when caught early. 5 year survival rates: Stage
1 greater than 90%, Stage 2 60-80%, Stage 3 approximately 50%, and stage 4 less
than 30%. Treatment for this type of cancer is usually dependent on age,
fertility or pregnancy plans. One procedure, LEEP, the loop electrosurgical
excision procedure carries an electrical current through a wire to remove abnormal
tissue. Cryotherapy freezes the abnormal tissue. Laser therapy uses a beam of
light to remove or even destroy the cells. Conization can also be used with a
knife and laser. (Boardman, 2018) In severe cases removal of the uterus, hysterectomy
is sometimes necessary. Radiation, chemotherapy and surgery can sometimes be
performed in other extreme cases.
However like any screening
test there is always a risk of inaccuracy in false negatives and false
positives. (National Cancer Institute, 2014) In some cases a pap smear can be
faulty and must be reported in an official capacity. Some examples of this
could be “drying artifact’ or “excessive blood.” The person reading the smear
could feel these are factors that affect the reading. Inflammation can also be
a problem in a Pap smear reading. Inflammation can be from infection or
Uterine cancer is defined as
the any invasive neoplasm of the uterine corpus and is the most common pelvic
gynecological malignancy in the United States. Uterine cancer can also be
labeled endometrial cancer. The most common type of uterine cancer specifically
is endometrioid adenocarcinomas. (Chiang, 2017) It is believed to have two
forms; type 1 or estrogen dependent and type 2, which is estrogen independent.
Uterine cancer can start in
small areas or “a diffuse multifocal pattern.” Health care professionals can
usually diagnose this type of cancer by the spreading pattern of the tumor.
Usually the tumor will grow from the original location. This can tell the
doctor how far along the cancer is. Later tumor growth is seen through
myometrial invasion and movement towards the cervix. The cancer itself can take
four different routes to spread outside the uterus. Direct or local extends
beyond the uterus. Lymphatic, referring to exposure to the pelvic, para-aortic,
and sometimes the lymph nodes. Hematologic goes further reaching the lungs,
liver, and bone metastatically. Lastly, “peritoneal/ transtubular spread
results in intraperitoneal implants.
Staging of Uterine cancer,
like most cancers, will depend on the amount of growth and spreading of the
tumors. Clinical stage 1, which is the most common for patients, is strict to
the uterus. Stage 2 involves a large amount of the cervix. Stage 3 “ vaginal extension,
adnexal mass, and/or suspicious retroperitoneal lymphadenopathy.” Stage 4
accesses the bowel and bladder and some other metastases around the body.
Although pap smears are
prominent for cervical cancer findings, it is not as helpful in uterine cancer.
According to my findings, there are actually no screening regimens for
asymptomatic women. The only screening mentioned is a transvaginal ultrasound,
which “determines the thickness in postmenopausal women.” In the suspicion of
abnormalities, biopsies can be taken. Uterine cancer usually includes both
surgery and radiotherapy. Other treatments follow a hormone regimen. Other
forms can use estrogen replacement therapy and Tamoxifen, which is usually used
for breast cancer but can be used on endometrium tissue as well. (Holman 2012)
Because of the early representation of the cancer, treatment is usually
successful and most do not progress past stage 1. Recurrences can happen and
usually do within 3 years of the original diagnoses, which occurs in half of
patients. (Holman 2012)(Uterine Cancer)
Symptoms of uterine cancer
can range from genital discharge, pain, weight loss, and change in bladder or
bowel movements. However, postmenopausal bleeding is said to diagnose up to 90%
of endometrial cancers. Another clinical finding would be glandular cells from
a pap smear on a postmenopausal woman. Some risk factors are obesity,
nulliparity, and late menopause. Diabetes and hypertension are also conditions
that. Less than 5% of this cancer is actually diagnosed when the woman is
asymptomatic can increase the risk of uterine cancer. (Uterine Cancer) Most of
the patients diagnosed with uterine cancer are obese, which can affect estrogen
levels. (Holman 2012)
Over 50,000 cases of uterine
cancer are diagnosed each year, leading up to 10,000 deaths per year. In women
alone, it leads to 4% of deaths related to cancer. 70-75% of cases are
diagnosed at stage 1. In 2009, the survival rate for uterine cancer was 83.1%.
(Chiang, 2017) A large majority of the population diagnosed are postmenopausal
and ages 50-65, average age of 61. White women have the largest risk of uterine
cancer in the United States compared to African American, Asian and Hispanic
women. However, African American women have a larger rate of death.
Interestingly, those women living in Asia or Africa have a much smaller rate of
uterine cancer than Asian and African American women in the United States.
Smoking actually has been shown to decrease your chance of endometrial cancer.
The use of contraceptive pills has also been said to be a protective measure
for women. (Holman 2012)
In conclusion, Pap Smears
can be resourceful ways of detecting cervical cancer but not at large uterine
cancers. Pap smears are a great screening method for obstetrician-
gynecologists and their patients to catch and prevent cervical cancer. By
detecting cervical cancer early, prognosis is very good and very likely in most
cases. These quick diagnoses from pap smears and other sources has made
cervical cancer a very uncommon cancer related death for women in the United
States. Unfortunately for developing countries, lack of medical resources and
research has made discovering cervical cancer difficult and fatal. With the
Bethesda System doctors from all over can classify cervical cancer the same
way. Pap smears are very accurate, but like any screening procedure there is
always the risk of false negatives or false positives.
Although Pap smears haven’t
been shown totally reliable to detect uterine cancer, there are several other
methods to find uterine cancer. The most obvious can be the presence of postmenopausal
bleeding in women, which diagnoses most of the cases. Transvaginal ultra sound
can be used to determine the state of the woman’s uterine tissue. These and a
few others have been said to be more reliable than Pap smears. Counterpart to
ruling out Pap smear findings, one source does tell that if glandular cells are
present than it might be uterine cancer. Like cervical cancer, uterine cancer
is most always found in early stages or stage 1 to be exact. This early
detection makes it only 4% of cancer related deaths in women.
In doing my research it was
clear to me that Pap smears are in fact helpful in detecting cervical cancer
but not as much in uterine cancer. I only found one source that mentioned
findings from a Pap smear for uterine cancer. This was entirely interesting to
me because they are in very similar areas of the woman’s reproductive system.
In doing more research, it makes sense that a pap smear rarely diagnoses
uterine cancer because it starts inside the uterus. The cervix being much lower
and away from the uterus makes it easier to obtain cells and much more
reliable. Finding cervical cancer can be much more direct and easily obtained.
Getting to the uterus safely is much more difficult.
In further research I believe it would be interesting to look further into minimally invasive ways to detect uterine cancer. Another topic is using the any findings from a Pap smear in detecting cervical cancer to relate to prevention of uterine cancer. Lastly, the result of cervical and uterine cancer on future pregnancy or on currently pregnant women.
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