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Breast-Conserving Surgery with Radiation Therapy

By Assoc. Prof. Dr. Yaowanush Kongdan and Dr. Paweena Luedthai

Historical Perspective

In the past, breast cancer surgery often involved removing the entire breast (mastectomy), with reconstruction considered only in later stages. Over time, breast-conserving surgery (BCS) emerged as an alternative, where the visible cancer or abnormalities detected in mammograms or ultrasounds are removed. This approach is followed by whole-breast radiation therapy to achieve recurrence rates comparable to mastectomy. Today, breast-conserving surgery combined with radiation therapy is a standard treatment. Surgeons are encouraged to prioritize this method, resorting to mastectomy only when breast preservation is not feasible.

Radiation Therapy After Breast-Conserving Surgery

Whole Breast Radiation (WBR) typically involves:

• Daily sessions (5 days a week) for 20–25 treatments, lasting about 4–5 weeks.

• Some patients may also receive boost radiation, focusing on the tumor site for an additional 1–2 weeks.

While effective, WBR can be inconvenient due to the daily hospital visits and may result in side effects such as fibrosis in surrounding tissues (skin, breast, lungs, or heart for left-sided tumors).

Partial Breast Radiation Therapy

For early-stage, low-risk breast cancers, partial breast irradiation (PBI) offers a more targeted alternative, focusing radiation on the tumor bed. This reduces side effects and minimizes the inconvenience of daily hospital visits. Candidates typically meet the following criteria:

• Tumor size ≤ 3 cm.

• No lymph node involvement.

• Positive hormone receptor status.

• Older age.

Techniques for Partial Breast Irradiation

1. External Beam Radiation Therapy (EBRT)

   • Targets the tumor bed with external radiation, completed in 1–2 weeks (about 10 sessions).

2. Brachytherapy

   • After surgery, catheters or balloons are placed in the tumor cavity. Radiation is delivered directly into these devices over 3–5 days, followed by catheter or balloon removal.

3. Intraoperative Radiation Therapy (IORT)

   • High-dose radiation is delivered to the tumor bed during surgery. Using lead shields to protect nearby tissues, this single-dose method is as effective as conventional WBR for selected patients.

Intraoperative Radiation Therapy (IORT)

Two main types of IORT devices available in Thailand include:

1. Cylindrical applicator systems delivering radiation directly downward (available at the National Cancer Institute and Siriraj Hospital).

2. Spherical applicator systems, such as Intrabeam 500 and 600, delivering radiation uniformly within the tumor cavity (available at Chulalongkorn Hospital and Namarak Hospital).

Evidence Supporting IORT

A study comparing IORT with traditional WBR included two groups:

1. Patients receiving IORT during surgery.

2. Patients undergoing post-surgery WBR.

Key findings:

• Mortality: IORT patients had a 4% mortality rate compared to 5% for WBR patients.

• Recurrence: IORT showed a slightly higher recurrence rate (1% difference), which was not statistically significant.

• Metastasis and mortality: WBR patients had higher mortality rates due to metastasis and secondary complications like heart and lung disease.

Procedure for IORT

1. Sentinel Node Biopsy

   • Performed under general anesthesia, with tissue sent for pathological examination (takes ~1 hour).

2. Tumor Removal

   • The tumor is excised along with a margin of healthy tissue.

3. Radiation Therapy

   • Radiation is delivered to the tumor cavity for 30–45 minutes.

4. Completion

   • Total surgery duration is approximately 2–3 hours.

Indications for IORT

Ideal candidates for IORT should meet the following criteria:

1. Age ≥ 45 years.

2. Tumor size ≤ 3.5 cm with a single lesion.

3. Positive hormone receptor status.

4. Non-lobular carcinoma.

5. A clear margin of ≥ 2 mm around the tumor.

Advantages of IORT

• Eliminates the need for post-surgery WBR in most cases.

• Reduces side effects on nearby organs like the heart and lungs.

• Provides comparable outcomes to conventional radiation therapy with fewer disruptions to the patient's life.

Conclusion

Advances in breast cancer treatment, particularly breast-conserving surgery with IORT, allow for effective cancer control with minimized side effects. Early detection remains critical, emphasizing the importance of regular self-examinations, mammograms, and ultrasounds. Small tumors (1–2 cm) can often be managed with tumor excision, intraoperative radiation, and hormonal therapy.

Disclaimer: Results may vary by individual. Consult a qualified physician for a tailored treatment plan.