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  • Nathan Riley, MD

Obgyno Wino Podcast Episode 95 - Breast Cancer Risk Assessment and Screening in Average-Risk Women

"The Tao, which others may call Natural Law or Traditional Morality or the First Principles of Practical Reason or the First Platitudes, is not one among a series of possible systems of value. It is the sole source of all value judgments. If it is rejected, all value is rejected. If any value is retained, it is retained. The effort to refute it and raise a new system of value in its place is self-contradictory. There has never been, and never will be, a radically new judgment of value in the history of the world. What purport to be new systems or…ideologies…all consist of fragments from the Tao itself, arbitrarily wrenched from their context in the whole and then swollen to madness in their isolation, yet still owing to the Tao and to it alone such validity as they posses.” ― C.S. Lewis


2017 Barbera d'Asti Le Orme "16 mesi" from Michele Chiarlo

PB #179, Published July 2017 (Reaffirmed 2019)


Five Pearls

1.



Breast cancer is really common

- accounts for 30% of all new cancers diagnosed in women

- a woman's lifetime risk of 12%

- 5-year survival rate is currently 90% (up from 75% in 1975)

- why has survival increased? better prevention/detection strategies!

Risk factors

- many women have no risk factors

- nulliparity and longer intervals between menarche and first birth are risk factors of hormone-sensitive breast cancers

- breastfeeding decreased the risk for hormone-sensitive breast cancer AND triple negative breast ca (i.e. estrogen-receptor (ER) negative, progesterone- receptor (PR) negative, and ERBB2-negative (formerly HER2-negative)

- any connection between HRT and breast cancer has not been fully clarified

- data from the Women's Health Initiative suggests that estrogen + progesterone poses a risk for breast cancer but not for estrogen alone

- family risk factors include a history of: breast, ovarian, fallopian tube, peritoneal, pancreatic, prostate, or colorectal cancers

- atypical ductal hyperplasia, atypical lobular hyperplasia, and lobular carcinoma in situ are benign histologic findings from breast mass biopsy that carry 4x risk of developing cancer in either breast in the future

- radiation to the chest (e.g. treatment of Hodgkin's lymphoma with therapeutic radiation), esp at young ages (<30) carries an increased risk of breast cancer


There are a variety of models for predicting individual breast cancer risk

- Gail, BRCAPRO, Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm, International Breast Cancer Intervention Studies (IBIS, also known as Tyrer–Cuzick), or the Claus model

- refer to a genetic counselor if you have any doubts!


Screening considerations

- may improve health outcomes if cancer is detected early but comes with the anxiety, cost, and false positives leading to inappropriate treatment

- breast self-exam and self-awareness, clinical exam, and mammography can all been a part of breast cancer screening depending on the patient

- optimal age to begin screening, screening intervals and the best combination of modalities are going to be dependent on the patient

- ACOG recommends shared decision making throughout the process of answers these questions




Mammography has a lot of benefits

- my mom says that they suck, but all data suggests that mammography decreases breast cancer risk, risk of requiring treatment for cancer, and life expectancy in all age groups (the American Cancer Society [ACS] and US Preventive Services Task Force [USPSTF] both agree on this)


Mammography also has relatively high false positive rates

- 60% with annual screening; 40% with biennial screening

- biopsy is indicated in 7% of patients who undergo annual screening and 5% who undergo biennial screening

- HRT use and dense breast tissue increase the likelihood of a false positive in women age 40-49

- false positives often come with additional financial costs, which are generally the responsibility of the patient


False positives lead to unnecessary diagnostic procedures

- some lesions probably aren't serious enough to warrant the stress and discomfort of diagnostic procedures like biopsy or excision (DCIS often falls into this category...)

- it's estimated that 10-20% of lesion

- unfortunately, there are ethical concerns with observing the natural progression of such lesions

- perhaps lower risk of overdiagnosis in older patients and less frequent screening

“1 in 8 women diagnosed with breast cancer with biennial screening from ages 50 to 75 years will be overdiagnosed. Even with the conservative estimate of 1 in 8 breast cancer cases being overdiagnosed, for every woman who avoids a death from breast cancer through screening, 2 to 3 women will be treated unnecessarily” - USPSTF


What about all of the radiation exposure that comes with mammography itself?

- 2 of 100,000 women aged 50-59 years who are screened biennially will die from mammography radiation-induced cancer

- 11 of 100,000 women aged 40-49 years who are screened annually

- these numbers are outweighed by far by the number of cancer deaths that are preventing through screening


When should mammography screening begin?

- ACS: given the opportunity at age 40, firmly recommended at age 45 for average-risk women

- USPSTF: 50 years

- ACOG agrees with starting age 40-50 based on risk factors

- shared decision making should revolve around the risks of overdiagnosis/overtreatment, anxiety that comes with screening, radiation associated w/ excess mammography versus the obvious benefits ALL in the context of their age and any other risk factors




Annual or biennial mammography?

- in younger women (<50), shorter interval screening improves outcomes but also comes with an increase in callbacks and biopsies

- in older women (50-74), biennial screening

- as such, ACS suggests annual screening at age 40, then transitioning to biennial screening at age 50

- USPSTF recommended biennial screening at all ages


Breast self-exam and self-awareness

- systematic self-exam is not recommended for women with average risk given high risk of false positives and that self-exams don't improve outcomes

- self-awareness: education around potential problems, such as pain, nipple discharge, redness, or swelling of the breasts so that she can bring them to the attention of a clinician

- 50% of cancers in women >50 years are detected by the women themselves

- 70% in women <50 years, biennial screening has lower false positive rate than annual screening


What's the utility of clinical breast exams?

- not necessarily helpful in average risk women, so make sure you are engaging your patient in shared decision making because women are not excited about these exams

- still recommended for high risk women, as it will pick up an additional 5% of invasive cancer cases when added to mammography

- screening interval is 1-3 years for 25-39 year olds

- annually if ≥40


When can we stop screening?

- breast self-awareness should continue for life

- age 75 is a pretty universal recommendation to stop mammography

- ACS suggests that mammography screening should continue even after age 75 if the patient has at least 10 years life expectancy

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