24 I KENYA NATIONAL CANCER SCREENING GUIDELINES
BREAST CANCER SCREENING
Globally, breast cancer is ranked 2nd in cancer incidence with 2,088,849 cases
(accounting for 11.6% of all new cases), while it is 4th in mortality with 626,679
[6.6% of all cancer deaths] (GLOBOCAN, 2018). Epidemiologic studies reveal
marked geographic variation worldwide in observed breast cancer burden.
Age-standardized incidence rates are higher in North America, Northern Europe,
Australia, and New Zealand averaging 84.8 – 94.2 cases per 100,000 persons,
compared to estimates of 40.3 per 100,000 women in Kenya (GLOBOCAN, 2018).
Some of the variation in breast cancer impact that is observed among countries
may be related to differences in their contemporary ethnic composition, such as
in Southern Africa (Fregene,2005).
In African women, breast cancer incidence peaks between the ages of 35 and 45 years, approximately 10 -15 years earlier than peak incidence for western countries outside of the western Africa region (Amir et al, 1994; Anyanwu, 2000; Hassan et al,
1992; Muguti, 1993, Amir et al, 1998, Ihekwaba, 1992).
Overall, breast cancer is the leading cancer in Kenya in incidence with 5,985 new cases, accounting for 12.5% of all new cancer cases, and 20.9% in women alone (GLOBOCAN, 2018). In the same period, it accounted for 9.2% of all cancer deaths, making it the third leading cause of all cancer deaths in the country. Available data shows that majority of breast cancer patients present in late stage, contributing to higher mortality and low overall survival. A study at Kenyatta National Hospital showed that 7.4% were diagnosed in tumor stage I, 33.7% in stage II, 29.7% in stage III, and 21% in stage IV. The study showed that breast lump is the commonest presentation (79.4%), followed by breast pain (26.8%). The average age at presentation was 48 years [range 21-84] (Othieno-Abinya et al, 2018).
RATIONALE FOR SCREENING
The incidence of breast cancer is on the rise, with 5,985 cases in 2018 compared to
4,465 in 2012 (GLOBOCAN, 2018). Screening for early detection therefore is an im-
portant aspect in the control of breast cancer. The primary goal of screening is to
increase detection of breast cancer in its early stages and hence improve prognosis
and reduce mortality.
The goal of these guidelines is to provide guidance on the appropriate use of screening tools for breast cancer and to help physicians, clinicians and women make informed decisions about screening for breast cancer.
KENYA NATIONAL CANCER SCREENING GUIDELINES I 25
Risk Factors For Breast Cancer
• Heredity & Family History
• Previous abnormal biopsy
• Chest wall radiation
• High breast density
• Reproductive history- nulliparity
• Early menarche
• No breastfeeding history
• Hormone Replacement Therapy (HRT)
• Lifestyle – obesity, physical inactivity, tobacco & alcohol
Heredity and Family History:
Having one or two affected first-degree relatives is associated with a higher risk of breast cancer, with a lifetime excess incidence of breast cancer of 5.5% and 13.3% respectively. The increase in risk is greater for younger women and also when the relative was affected at a younger age (Collaborative Group, 2001).
Women with BRCA1 and BRCA2 mutations have a cumulative lifetime risk of breast cancer of 57%; these genes are hereditary. It is therefore important to assess cancer history from both the paternal and maternal side (Collaborative Study Group, 2000).
Breast cancer and ovarian cancer may also occur in other genetic syndromes. Assessment, counselling and potential genetic testing for these syndromes will be considered by Medical Geneticists or Physicians.
Biopsy Proven Atypical Hyperplasia or Lobular Carcinoma in situ
Women with atypical hyperplasia or lobular carcinoma in situ in previous breast biopsies, have a four-fold increased risk of cancer which persists for at least 25 years (Hartman et al,2005).
Women with a history of chest wall radiation as treatment for another cancer have up to a ten-fold increased risk for breast cancer (Terenziani M et al, 2013).
The risk of breast cancer due to radiation exposure during mammography is negli- gible compared with the expected mortality reduction that can be gained through screening (Yaffe, 2011).
Women with extremely dense breasts have about a two-fold increased risk compared to women with breasts of average density (Gierach, 2012).
Women with earlier age of menarche and/or later age of menopause (Collaborative Group, 2012) have an increased risk of breast cancer, mediated in part by the increased number of menstrual cycles and the longer lifetime exposure to estrogen and progesterone.
Nulliparity also increases a woman’s risk of breast cancer, and every live birth reduces the relative risk by about 7%. Women 30 years or older at the time of their first live birth have a higher risk of breast cancer than women having their first child at a younger age (Nelson, 2012).
Breastfeeding can lower breast cancer risk, especially if a woman breastfeeds for longer than 1 year (Collaborative group, 2002).
Hormone Replacement Therapy:
Prolonged use of combined estrogen-progesterone hormone replacement therapy
(HRT) increases the breast cancer by 15% though this returns to baseline within about
2 years of stopping HRT. Estrogen therapy alone increases breast cancer risk as well, but
the increased risk is lower than for combined therapy (Beral et al 2011).
Lifestyle risk factors
• Obesity: Obesity is associated with an increased risk of postmenopausal breast cancer, as is weight gain throughout adulthood. Obesity also negatively affects prognosis of early stage breast cancer (Ligibel J, 2011).
• Physical Activity: Breast cancer risk is reduced by about 25% among physically active women compared to the least active women (Friedenreich CM, 2011).
• Alcohol Consumption: Regular consumption of as little as one drink per day elevates the risk of breast cancer by about 4%. (Mandelson
et al, 2000). The risk increases steadily with increasing consumption regardless of the type of alcohol consumed (Seitz HK et al, 2012).
• Tobacco Use: Studies have demonstrated that there is a causal association between active smoking and second-hand tobacco smoke and breast cancer (Collishaw et al, 2009).
SCREENING INTERVENTIONS AND FREQUENCY OF SCREENING
Mammography is the recommended method of screening for women in the average risk population
(NCCN 2016). Mammography is the only screening modality shown to reduce breast cancer mortality.
Possible risks of mammography are listed in the table below.
Risks of Mammography
False negative results – this gives a false sense of security that may delay diagnosis
False positive results – associated with anxiety and requiring extra unnecessary tests
Clinical Breast Examination (CBE) & Ultrasound
CBE should be considered as part of a physical examination and used as an opportunity to discuss and educate the woman on breast health.
It should not be considered as a replacement for mammography screening.
Ultrasound, when available and if conducted by a competent clinician, should be considered as an adjunct to CBE in women between 35 and 39 years.
Breast Self-Examination (BSE) and Awareness
BSE is not recommended as a screening method.
However, women should be encouraged to be aware and to report changes in their
breasts, such as nipple discharge, rash on nipples, inversion, dimpling or new mass in
the breast or axilla.
The healthcare provider should discuss and educate the women about their breast health and promote breast awareness.
Key messages on breast self-examination and breast awareness:
• Knowledge of what is normal in your breast is important to
maintain good breast health
• Discuss breast health and awareness with your healthcare provider
• Report any abnormality noted in your breast
• Self-breast examination and clinical breast examination are
complementary but do not substitute mammography as
• Asymptomatic women above 40 years require a baseline
• Breast cancer also occurs in men though rarely. They need
to have breast awareness and not routine screening
MRI is not recommended for routine screening the average risk population.
MRI may be used for screening in select high-risk populations or in specific circumstances
as determined by a clinician such as previous lumpectomy, radiation or trauma to breast.
Ultrasound is not recommended for routine screening for the average risk population.
It may be used to complement mammography in situations where patients have increased
Tomosynthesis, thermography, elastography and PET scans are not recommended for screening of breast cancer. Tomosynthesis may be used in specific circumstances to complement mammography as may be determined by a radiologist.
BSE,CBE and ultresound are not screening modalities, but they aid in early detection of breast cancer
The target population for screening will depend on the risk of the patient, which could
be defined as high risk or average risk as defined below (NCCN 2016).
An assessment of risk for breast cancer should be done for all women considering age, medical history, family history, and other associated risks in determining her breast cancer screening needs. This guideline recommends the Tyrer-Cuzik Model for Risk assessment model for assessment of risk of developing breast cancer (see Annex). Assessment of risk stratifies women into two risk categories as follows:
• Average Risk Population – More than 80% of breast cancer occurs in
women in the average risk population.
• High Risk Population
o Women Requiring More Intensive Screening
o Criteria for Referral to Medical Genetics
AVERAGE RISK POPULATION
The average risk population, is defined as that population of women who do not exhibit
any of the risk factors that define the high-risk population. The clinician should discuss
the benefits and risks of screening specific to each age group. (NCCN 2016).
• Women with signs and symptoms suggestive of breast cancer
• Women with a previous diagnosis of ductal carcinoma in situ or
invasive breast cancer
Recommendations per age category for Women with average risk are provided below.
|25 – 34 years||CBE every 3 years
Mammogram is not recommended
|1 to 3 years|
|35 – 39 years||CBE and Ultrasound OR mammography*||1 to 3 years|
|40 – 55 years||CBE + mammography||Annual|
|56 – 74 years||CBE + mammography||Every 2 years|
|75 years and older||Consider individual health factors and woman’s
preference to continue screening
|Discuss with patient|
* The balance of benefits and risks is not great enough to recommend routine screening.
Clinical judgment may be used to adjust the frequency of screening considering individual differences.
Women who have had surgery for breast augmentation, breast reduction or sex-reassignment should follow the same recommenda- tions below for mammographic screening as those in the average risk population. The clinician should clearly state presence of breast implants in the mammography requisition form.
HIGH RISK POPULATION
Women in the high-risk population require more intensive screening and/or genet-
ic counseling. Women with the following characteristics are classified as high risk for
breast cancer. Women who do not fulfill any of the four criteria should be classified in
the average risk group.
Affected first degree relatives Previous abnormal breast biopsy Previous chest wall radiation
Previous breast cancer
The screening recommendations for these are as follows:
1. Women with one or two first degree relatives with invasive breast cancer, but
who do not meet the criteria for referral to Medical Genetics (See criteria below).
• CBE – starting at age 25 years
• Annual mammography starting 10 years younger
than the youngest case in the family, but no
earlier than age 25 and no later than age 40;
• Complementary imaging like ultrasound and MRI
in addition to the above where justified.
2. Women with a breast biopsy showing atypical hyperplasia or lobular carcinoma in
situ and following surgical management to rule out invasive carcinoma:
• CBE every 6-12 months
• Annual mammography
3. Women with a history of chest wall radiation (i.e. mantle radiation for treatment of
Hodgkin’s lymphoma) at age 30 or younger:
• Annual mammography and MRI starting 5 years
after radiation given, but starting no earlier than
age 25 and no later than age 40
• Annual CBE
4. Women with previous breast cancer require screening of contralateral breast
• CBE every 6-12 months
• Annual mammography
Criteria for referring high risk women for genetic counseling.
Some women in the high-risk population will require referral for genetic testing and counseling.
These include the following:
1. An individual with a number of relatives with breast and/or ovarian* cancer
(e.g., three or more cases )in two or more generations, at least
one case with onset under the age of 5O)
2. Bilateral primary breast cancer
3. Breast cancer at age 35 or younger
4. Breast cancer that is hormone receptor negative and HER2 negative (triple
negative), age 6O or younger
5. Primary breast and primary ovarian cancer in the same individual
6. Male breast cancer, age 65 or younger, or at any age if with close famil history
of breast cancer
7. Confirmed BRCA1 or BRCA2 mutation in the family
RISK ASSESSMENT ALGORITHM
SCREENING AT VARIOUS HEALTHCARE LEVELS
The table below shows the breast cancer screening activities to be performed at the various levels of service delivery of Kenya Essential Package for Health (KEPH):
Volunteers (CHVs) &
|1||Community||Community Health||Breast awareness
|3||Health Centres||Clinical officers||Breast awareness
|5||County/||.. Nurses||Breast awareness|
|General surgeon||CBE/ BSE/ Biopsy|
Mobilization/ Breast awareness/ CBE
BREAST CANCER SCREENING AND REFERRAL ALGORITHM
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