Today, I reviw, link to, and excerpt from The Curbsiders‘ #426 Breast Cancer for the PCP With Dr Sandhya Pruthi.*
*Heublein M, Pruthi S, Kryzhanovskaya E, Williams PN, Watto MF. “#426 Breast Cancer for the PCP”. The Curbsiders Internal Medicine Podcast. thecurbsiders.com/category/curbsiders-podcast February 12, 2024.
All that follows is from the above resource.
Transcript available via YouTube
Join us as Sandhya Pruthi, MD talks us through basics of breast cancer, specifically how to share a new diagnosis with a patient, the spectrum of disease from favorable to more aggressive, and the basics of what to expect with initial treatment. Feel more confident sharing a new diagnosis of breast cancer and supporting your patients through this journey.
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Show Segments
00:00 Introduction
02:18 Getting to Know Dr Sandhya Pruthi
09:49 Picks of the Week
12:35 Case 1: Diagnosis and Treatment of ductal carcinoma in situ (DCIS)
21:24 Risk Stratification and Active Surveillance for DCIS
23:43 Genetic Testing Recommendations
28:08 Case 2: Evaluation and Diagnosis of a Breast Lump
39:14 Invasive Ductal Carcinoma
47:49 Initial Management of invasive ductal carcinoma (IDC)
48:19 Preoperative Discussion and MRI
49:19 Lumpectomy and Sentinel Lymph Node Biopsy
50:16 Radiation and Hormonal Adjuvant Therapy
51:46 Considerations for Chemotherapy
55:51 Signs of Late Recurrence or Metastasis
58:20 Screening Guidelines and Age
01:02:25 Importance of Breast Self-Awareness
Breast Cancer for the PCP- Pearls
- Breast cancer is a heterogeneous disease. Understanding breast cancer biology gives insight into the potential treatments and prognosis.
- Low risk to high risk breast conditions exist across a spectrum. Benign fibrocystic changes—> atypia—> DCIS (grade 1, 2, and 3) —> Invasive Cancer (hormone receptor positive more favorable than estrogen/progesterone receptor (ER/PR) negative, HER2 negative more favorable than HER2+, low Ki67 proliferation score more favorable than high Ki67 score; etc)
- Education is key! Helping patients anticipate possible outcomes of biopsies helps prepare them for receiving results. Patients who understand the basics of their breast cancer biology can make more informed treatment decisions.
- Current recommendations for treatment of ductal carcinoma in situ (DCIS) include lumpectomy +/- radiation therapy vs mastectomy. Patients may also be treated with anti-estrogen medications.
- Ongoing research is helping identify cases of DCIS that are less likely to progress to invasive ductal carcinoma (IDC) and allow deescalation of treatment or options for active surveillance.
- Invasive ductal carcinoma is similarly heterogenous, and treatment should be tailored to the individual patient based on their cancer biology.
- PCPs should be aware of the risk of late recurrence of IDC, especially hormone receptor positive cancers, which can manifest decades later.
Breast Cancer Biology: the 101
Breast cancer is a heterogeneous disease. Understanding breast cancer biology gives insight into the potential treatments and prognosis.
Ductal Carcinoma in Situ (DCIS)
DCIS has a very favorable prognosis. Dr Pruthi describes DCIS as a “contained cancer” within the glands or milk ducts of the breast. At this stage, it does not have an opportunity to spread. DCIS is typically diagnosed after mammographic findings of asymptomatic calcifications. It is somewhat controversial if DCIS is considered a “precancer” vs a “contained cancer”. There is a risk that DCIS can transition into invasive cancer, but it is a heterogeneous disease and not all will progress (Grimm 2022). About 50,000 patients in the US will be diagnosed with DCIS– much lower numbers than the more than 200,000 who are diagnosed with invasive ductal carcinoma (IDC) (ACS 2024).
Patient Communication around a new Cancer Diagnosis
Dr Pruthi recommends pre-education for patients going in for a breast biopsy. Prepare patients that biopsy results of mammographic calcifications can span a spectrum from benign fibrocystic changes to atypia to DCIS. This prep work will make the discussion about the results much easier.
With a new cancer diagnosis, Dr Pruthi highlights that it is ideal to share this news in person, but sometimes that’s not feasible. When she calls a patient with a new diagnosis of DCIS, she makes sure to stress that there is no role for chemotherapy in treatment of DCIS.
DCIS Treatment
Standard Treatment
Surgical removal of DCIS is currently standard of care– the size of the DCIS and patient preferences help decide if lumpectomy or mastectomy is preferred. In patients with lumpectomy, radiation is typically suggested, as radiation + lumpectomy is considered to confer equal risk of local cancer recurrence as mastectomy. In some patients at low risk and at older age, radiation is not needed even after lumpectomy (Peppercorn 2017, Farante 2022). Some patients may benefit from oral hormonal blockers such as tamoxifen or aromatase inhibitors for estrogen receptor (ER) positive cases (Hwang 2020).
DCIS Treatment
Standard Treatment
Surgical removal of DCIS is currently standard of care– the size of the DCIS and patient preferences help decide if lumpectomy or mastectomy is preferred. In patients with lumpectomy, radiation is typically suggested, as radiation + lumpectomy is considered to confer equal risk of local cancer recurrence as mastectomy. In some patients at low risk and at older age, radiation is not needed even after lumpectomy (Peppercorn 2017, Farante 2022). Some patients may benefit from oral hormonal blockers such as tamoxifen or aromatase inhibitors for estrogen receptor (ER) positive cases (Hwang 2020).
Genetic Testing for Breast Cancer
Per American Cancer Society (ACS) recommendations, patients diagnosed with breast cancer (DCIS or invasive) under the age of 60 should be offered to meet with a genetic counselor to consider genetic testing (Desai 2020). Dr Pruthi highlights that genetic testing is much less expensive than it used to be (now around $250) and can test multiple genes as compared to older panels. Since our recording, a new guideline from ASCO- Society of Surgical Oncology suggested extending germline mutation testing to all patients diagnosed with breast cancer under the age of 65 (Bedrosian 2024).
Any woman with a strong family history of breast cancer (>1 family member with breast cancer before age 50, or ovarian cancer, male with breast cancer, family member with both breast and ovarian cancer) should be considered for genetic testing. Ideally the person with cancer should be tested before family members, but if this is not possible, it is reasonable to refer your patient with a positive family history to a genetics counselor (NCCN 2020).
Testing can look for a large panel of genes, beyond just BRCA mutations. CHEK2, PALB2, ATM are moderate penetrance genes that significantly increase the risk of breast cancer, though less than BRCA mutations. Genetic testing from more than 5 years ago may have had more limited panels, so patients that were tested some time ago may be recommended to retest a more expanded panel (Graffeo 2022).
Evaluating a Breast Lump
Concerning lumps are firm, fixed, large, and/or associated with skin changes. The first step to evaluating a palpable breast lump is a bilateral diagnostic mammogram +/- focused ultrasound. Dr Pruthi highlights that it is not appropriate to order a routine screening mammogram for patients who are overdue for screening if they have a new breast complaint– the patient requires diagnostic imaging so that the radiologist is alerted to the concern in question. In rare cases, imaging (diagnostic mammogram and ultrasound) can provide a false negative. If you have a high risk patient/lump and the imaging is negative, you should pursue a tissue diagnosis, so it is important to have a patient follow up after imaging to discuss next steps. Dr Pruthi highlights cases of invasive lobular carcinoma that have been missed on imaging.
Dr Pruthi does not recommend a breast MRI to evaluate a high risk breast lump that has negative mammogram/ultrasound. Breast MRIs are expensive and with a high risk lump you still need a tissue diagnosis (even if MRI is negative).
Invasive Breast Cancer
Invasive ductal (IDC) and lobular are most common. Mucinous, anaplastic, metaplastic are rare, more aggressive invasive types of breast cancer.
Understanding the biology of the specific patient’s breast cancer helps to guide treatment recommendations. Hormone markers (estrogen, progesterone) and HER2 sensitivity are essential as ER/PR+ cancers can be treated with oral hormone blockers and HER2+ cancers have specific anti-HER2 therapies. Ki67 is a proliferative marker which is tested on hormone positive tumors– high proliferation suggests more aggressive cancer so helps with risk stratification (Kreipe 2022). Oncotype DX or MammaPrint are multigene panels that can further risk stratify patients to suggest how aggressive treatment should be (Xin 2017)
In some cases an MRI pre-operatively can be helpful for surgical planning to assess the extent of disease, Dr Pruthi suggests. The downside to getting a breast MRI is the high false positive rate, this could lead to additional biopsies or potentially over treatment. Dr Pruthi’s expert opinion is that these are most helpful in patients with denser breasts (in whom size of tumor is harder to estimate on mammogram) and patients who are leaning more toward lumpectomy (instead of mastectomy).
IDC Treatment
After diagnosis of IDC, patients may undergo a range of treatments based on their cancer biology.
In less common situations, neoadjuvant therapy can be suggested for locally advanced cancers, triple negative (ER/PR-/HER2-) IDC, or cancers with other high risk features. Treating with chemotherapy and/or anti-HER2 immunotherapy (like trastuzumab) before surgery can help expand surgical options by shrinking the tumor early (Barchiesi 2020).
