SCORE - Breast Flashcards
DCIS is defined as…
a clonal proliferation of malignant epithelial cells that are confined within the basement membrane of the mammary ducts
There are two major histologic subtypes of DCIS:
- Comedo: notable for the presence of central necrosis, large pleomorphic nuclei, numerous mitotic figures and microcalcifications. This subtype is associated with the worst prognosis.
- Noncomedo: notable for the presence of papillary, micropapillary, or cribriform architecture. This subtype does not demonstrate central necrosis or mitotic figures.
Nuclear grade is classified as…
low, medium, or high
based on both the morphology of the nucleus and by the mitotic index
High-grade DCIS is associated with the worst prognosis as it has the most aggressive biologic characteristics and is associated with the highest local recurrence rates.
Discuss the incidence of DCIS and natural history
- Incidence: 32.5 cases per 100,000 women; 25% of all breast cancers diagnosed are DCIS
- Psx: suspicious microcalcifications on mammography
- DCIS left untreated: invasive cancer oftentimes develops near the same site
Identify risk factors associated with development of DCIS
- Risk factors for DCIS are similar to those for invasive breast cancer - increased estrogen exposure
- FHx of breast cancer
- nulliparous
- children at a later age
- obesity
- BCRA1 and BRCA2 genes
Describe the primary approaches to breast cancer (DCIS and invasive types) prevention.
- Screening mammogram: start at 50 yrs, every 2 yrs, stop 74 yrs
- >20% lifetime risk (high risk): mammogram and breast MRI q1yr, breast exam q6mo
- Significant FHx: screen 5 - 10 yrs prior to youngest age of family dx
- BRCA mutation: screening at 25 yrs with an annual breast MRI, add mammography at 30 yrs
Describe the most common presenting signs (mammographic abnormality most common) and symptoms (usually asymptomatic) for DCIS.
- ~90% of DCIS psx: abnormal screening mammography
- Mammography: grouped, pleomorphic, fine linear microcalcifications
- Rarely, patients with DCIS will present with symptoms including a palpable breast mass, skin changes, or nipple discharge
Given a patient presenting without breast symptoms and physical findings such as a mass or nipple discharge, order the appropriate workup for a patient with an abnormal screening mammogram.
-
Abnormal screening mammogram → diagnostic mammogram
- inc magnifx, different angles, characterize lesion, BI-RADS
- Diagnostic US may be required: differentiate solid and cystic
- W/u for abnormal lesion dependent on BI-RADS category:
- BI-RADS 1/2 → return to routine screening mammograms
- BI-RADS 3 → probably benign → f/u 6 mo w/ mammogram
- BI-RADS 4/5 → image-guided biopsy → tissue diagnosis
Given a patient with a cluster of suspicious microcalcifications seen on mammography, discuss biopsy options to further evaluate this abnormality.
- Stereotactic biopsy is the preferred method of biopsy: outpatient setting, breast placed into stereotactic device that localizes the lesion on a 2D plane using mammograph, 3-mm core needle
- Breast lesion vague on mammography, US, and MRI; or too posterior or too close to the nipple → needle-localized breast biopsy: guide wire placed into breast over site of lesion → surgical biopsy
Given a patient with newly diagnosed DCIS, discuss the advantages and disadvantages of the use of MRI prior to surgery.
- MRI increasingly used in the pre-operative evaluation of patients with known DCIS: determine extent, evaluate for tumors in contralateral breast, and evaluate for multicentric tumors
- Advantages to pre-op breast MRI: evaluate tumor physiology, enhanced on contrasted MRI studies which makes them very detectable
- Disadvantage to breast MRI: low specificity, high false-positive rate
Discuss the TNM staging for DCIS
- TNM system: size of primary, lymph node involvement, metastases
- DCIS is a pre-cancerous lesion as the dysmorphic cells are confined within the basement membrane of a mammary duct and have not invaded into the surrounding cell layers
- Since DCIS is a pre-cancer, it is considered to be TisN0M0 or Stage 0 breast cancer.
Given a patient with DCIS identified following core needle biopsy, counsel the patient regarding treatment options, including breast conservation therapy versus mastectomy with or without reconstruction, and describe the role of sentinel node biopsy in DCIS.
- The aim of breast conservation surgery in the setting of DCIS: negative margins, cosmetically acceptable result.
- DCIS pts candidates for BCS: limited to one quadrant/section, cosmetically acceptable results, negative margins
- Total mastectomy considered: multicentric DCIS, centrally located disease, large lesions, inadequate surgical margins s/p BCS, prefer mastectomy, if adjuvant radiation is contraindicated
- Total mastectomy for DCIS → offer immediate breast reconstruction
- Risk of nodal mets with DCIS is less than 3%. However, eval of axillary nodes via SLNBx may be considered with lesions >4 cm, palpable breast lesions, microinvasive disease, high-grade disease, or with suspicious axillary lymph nodes on exam or US.
- All patients undergoing a total mastectomy for DCIS should undergo a concomitant SLNBx - this procedure not possible s/p mastectomy
Given a patient with DCIS undergoing breast conservation therapy, discuss the need for adjuvant radiation therapy and the use of tamoxifen in hormone receptor-positive patients.
- Radiation therapy: standard of care in DCIS s/p BCT
- may be omitted if small foci of low-grade, neg margins, adv age, extensive co-morbidities.
- After lumpectomy, radiation therapy reduces the risk of local recurrence of both invasive and non-invasive breast cancer.
- S/p BCT - hormonal therapy (tamoxifen) depends on receptor status
-
ER-positive DCIS s/p BCT - post-operative tamoxifen for 5 yrs
- Prevent ipsilateral recurrences, new events of breast cancer
Given a patient with palpable asymmetric breast density and excisional biopsy demonstrating DCIS measuring 3 cm in diameter and multiple positive margins, recommend either re-excision versus total mastectomy with or without reconstruction for margin control to obtain negative margins.
- 2 mm or larger margin - lower risk of a local recurrence
- S/p BCT w/ + margins: re-excision versus total mastectomy
- extent of DCIS, amount of breast removed, margin involvement
- one margin: re-excision + adj radiation therapy
- multiple margins: total mastectomy considered
Given a patient with suspicious microcalcifications seen on screening mammogram, describe the appropriate workup based on the latest NCCN guidelines.
Treatment should be based on the BI-RADS category
- BI-RADS 0 (incomplete) → dx mammogram or breast US
- BI-RADS 1 (negative) or 2 (benign) → regular screening mammograms.
- BI-RADS 3 (likely benign) → dx mammogram in 6 mo, q6-12 mo x2
- resolved or stable → normal screening mammograms
- more suspicious → core needle bx
- BI-RADS 4 (suscpicious) or 5 (suggests cancer) → core needle bx
Given a patient with a 5-mm, low-grade DCIS treated with segmental mastectomy with widely negative margins, discuss the potential of omission of radiotherapy in favor of observation based on low predicted recurrence rates without the use of radiotherapy.
- Radiation therapy: reduce recurrence in ipsilateral breast; does not reduce risk of recurrence in the contralateral or decrease mortality
- Low-risk disease + negative margins: radiation therapy can be omitted
- Omission of radiation therapy should be considered in patients with an ipsilateral risk of recurrent disease that is approximately equal to their risk of developing contralateral disease.
In a patient with hormone receptor-positive DCIS treated with segmental mastectomy and radiation therapy, discuss the risks/benefits of adjuvant tamoxifen therapy.
50% to 75% of DCIS have estrogen or progesterone receptors
- Tamoxifen for ER-positive DCIS s/p breast-conserving treatment.
- Therapy for 5 years to prevent ipsilateral and contralateral recurrence
- Risks: endometrial cancer and thromboembolic events
- Added endocrine therapy: less risk of recurrence, no mortality benefit
Following initial treatment for DCIS, recommend that the patient undergoes annual mammographic examination following breast-conserving surgery.
- Following BCT for DCIS: PE q6mo x5 yrs → q1 yr PE
- The patient should also undergo an annual diagnostic mammogram
- Special attention should be paid to the ipsilateral breast following breast conserving surgery as the majority of DCIS recurrences occur in close proximity to the site of initial disease.
Identify risk factors associated with recurrence of disease, including use of the Van Nuys scoring system, and the risk of the recurrence being invasive versus non-invasive breast cancer.
The Van Nuys scoring system is a scoring system which determines whether patients are at an increased risk of developing recurrent breast cancer.
- The scoring system takes into account the age of the patient, the size of the primary tumor, the margins following surgical resection, and the findings on pathologic examination. Factors associated with a higher risk of recurrence include younger age, a large primary tumor, close margins, and higher grade tumors as seen on pathology.
- Patients with scores of 4-6 have an average recurrence rate of 2%, of which 0% of cancers were invasive breast cancer.
- Patients with scores of 7-9 have an average recurrence rate of 22%, of which 46% of cancers were invasive breast cancer.
- Patients with scores 10 and higher had an average recurrence rate of 53%, of which 43% of cancers were invasive.
Describe the blood supply to the breast
The breast receives 2/3 of its blood supply from the inferior mammary artery and 1/3 from the lateral thoracic artery.
Describe the lymphatic drainage from the breast.
- 75% through axillary nodes; 25% through internal mammary nodes.
- Three levels of axillary lymph nodes:
- Level I – lateral to the pectoralis minor
- Level II – deep to the pectoralis minor
- Level III – medial to the pectoralis minor
