Cirugía 2025 15/09/2025

Summary

The lecture reviews the diagnosis and treatment of breast cancer, emphasizing the shift from routine, extensive surgery toward individualized care that preserves the breast and limits axillary surgery when oncologically appropriate.

1. Changes in breast cancer surgery

• Historically, treatment often involved radical mastectomy, removing the breast, nipple and skin, pectoral muscle, and axillary lymph nodes.
• Modern treatment is more tailored:
  • Breast-conserving surgery removes the tumor with an acceptable margin.
  • Mastectomy may preserve the skin and, in selected cases, the nipple–areola complex, often with reconstruction.
  • Sentinel lymph node biopsy can replace routine axillary lymph node dissection for many patients.
• Avoiding unnecessary axillary dissection matters because it can cause lymphedema, altered sensation, and other complications.

2. Incidence and risk factors

The lecturer describes breast cancer as the most common cancer in women in Uruguay and a leading cause of cancer mortality. He notes that Uruguay has both high incidence and high mortality.

Non-modifiable risk factors discussed include:

• Female sex, although breast cancer can also occur in men.
• Increasing age. The lecture notes that cases in women under 35 are increasing and may be more aggressive.
• Inherited susceptibility, estimated to account for 5–10% of cases, and family history.
• Early menarche and late menopause, which increase lifetime exposure to menstrual hormonal cycles.
• Prior radiation exposure, particularly radiotherapy at a young age.

Modifiable or potentially modifiable factors include having children later or not having children, obesity, diet, and physical inactivity. The lecturer recommends healthy eating, preventing obesity, and exercising.

3. Pathology and tumor subtypes

Breast cancers commonly arise from the ducts or lobules, producing ductal or lobular tumors.

A proposed progression for some ductal cancers is:

1. Normal duct tissue develops hyperplasia.
2. Hyperplasia with atypia may develop.
3. This may progress to ductal carcinoma in situ (DCIS).
4. DCIS may progress to invasive ductal carcinoma.

The lecturer estimates that roughly 75–80% of tumors are invasive and 20–25% are in situ, with increased screening helping detect more in-situ disease.

A core (thick-needle) biopsy is preferred to establish tissue architecture, distinguish in-situ from invasive disease, and assess tumor markers. Fine-needle aspiration provides cells but does not supply the same information about invasion or tumor profile.

Immunohistochemistry evaluates estrogen and progesterone receptors, HER2, and the proliferation marker Ki-67. The lecture groups tumors into:

• Luminal A: Hormone-receptor positive, HER2 negative, generally lower Ki-67, and a more favorable prognosis.
• Luminal B: Hormone-receptor positive, often with higher Ki-67 and/or less progesterone-receptor expression.
• HER2-positive: HER2 positive and hormone-receptor negative.
• Triple-negative: Estrogen-, progesterone-, and HER2-negative.
• Luminal/HER2 hybrid: Hormone-receptor positive and HER2 positive.

Ki-67 cutoffs can vary and should be interpreted alongside the overall receptor profile and clinical context. In the Q&A, the lecturer gives approximately 14% as a general cutoff while stressing that interpretation is not based on that number alone.

4. Diagnosis and imaging

The lecturer presents three pillars of diagnosis:

1. Clinical assessment
2. Imaging
3. Pathology

• Mammography uses craniocaudal and mediolateral-oblique views to locate and characterize lesions.
• Breast and axillary ultrasound can assess suspicious lymph-node features and guide biopsy.
• MRI may be considered for high-risk patients and in selected cases, such as extensive disease, DCIS, or invasive lobular carcinoma. The lecture notes that lobular cancer can be multifocal or present in both breasts.
• BI-RADS is described as a standardized system:
  • Categories 1–2: Negative or benign findings.
  • Category 3: Probably benign; the lecturer describes follow-up imaging at six-month intervals for two years.
  • Category 4: Suspicious; subdivisions A, B, and C correspond to progressively higher estimated malignancy probabilities.
  • Category 5: Highly suspicious. The transcript cuts off before the lecturer completes the stated probability.
  • Category 0: An incomplete study requiring additional imaging or assessment.

5. Surgical treatment and margins

Surgery may be curative in some cases and is often part of treatment alongside other therapies.

• For invasive tumors, the lecture describes an acceptable margin as no tumor on ink—the tumor does not touch the ink-marked edge of the surgical specimen.
• For in-situ tumors, the lecture states that a margin of at least 2 mm is sought.
• The overall goal is conservative treatment when it can be performed safely with acceptable oncologic margins.

6. Sentinel lymph node biopsy and axillary treatment

The sentinel node is the first lymph node expected to receive drainage from the breast tumor. A tracer or dye is injected into the breast or around the tumor to identify it. The lecture mentions patent blue dye, indocyanine green, and technetium-99.

If the sentinel node is negative, the lecturer says further axillary dissection can generally be avoided.

The lecture distinguishes:

• Macrometastases: Deposits larger than 2 mm.
• Micrometastases: Deposits measuring 0.2–2 mm.
• Isolated tumor cells: Deposits smaller than 0.2 mm.

The lecturer states that micrometastases and isolated tumor cells generally do not require axillary dissection, while macrometastases may prompt it. The transcript’s wording about the exact macrometastasis threshold is unclear.

After neoadjuvant treatment, the lecturer says that any tumor finding in the axillary nodes at surgery—including macro- or micrometastases or tumor cells—would lead to axillary dissection.

7. Neoadjuvant therapy

Neoadjuvant therapy is treatment given before surgery. The lecture identifies potential candidates as patients with:

• Initially inoperable or locally advanced disease.
• Inflammatory breast cancer.
• Significant axillary involvement or clinically advanced nodal disease.
• T4 disease, including skin involvement.
• HER2-positive or triple-negative tumors larger than approximately 1.5 cm.
• Tumors for which shrinking the lesion could allow breast-conserving rather than more radical surgery.

The lecturer notes that HER2-positive and triple-negative cancers may have substantial responses to preoperative treatment. A complete pathological response may also change axillary management. Whether surgery can safely be omitted after a complete response remains under study; the lecture does not present this as established practice.

8. Risk-reducing surgery and screening

For people with pathogenic inherited mutations—examples given include BRCA1, BRCA2, ATM, and PALB2—a risk-reducing mastectomy may be considered. It reduces risk but does not eliminate it, because some breast tissue may remain.

For BRCA1/2 carriers, the lecturer also mentions monitoring for other associated cancer risks and, in some cases, considering removal of the fallopian tubes and ovaries.

A patient diagnosed with cancer in one breast and found to carry a mutation may consider treating the affected breast and having risk-reducing surgery on the other side.

The lecture recommends screening mammography beginning annually at age 40. In the Q&A, the lecturer agrees that people at high risk may have annual MRI screening, including from a younger age, and says this can be available through CUDIM. The lecturer also says breast reconstruction may be provided for patients undergoing breast cancer surgery.

9. Overall message

Breast cancer care should be planned by a multidisciplinary team. Treatment should be matched to the tumor’s biology and extent, aim to preserve the breast and avoid unnecessary axillary surgery where possible, and incorporate screening, genetic risk assessment, systemic therapies, and reconstruction when appropriate.

Speakers and sources featured

• Dr. Juan Cosa — Assistant at Surgical Clinic A and the main lecturer.
• Unidentified students or class participants — Brief comments, technical checks, and questions during the online lecture.
• Sources mentioned by the lecturer: NCCN guidelines; Globocan; Uruguay’s Honorary Commission for the Fight Against Cancer; and surgical and pathology textbooks. Some textbook names are unclear in the auto-generated subtitles.