Published: Thursday, May 03, 2007

1. Recommendations for locoregional breast radiotherapy after breast conserving surgery
2. Recommendations for locoregional radiotherapy after mastectomy
3. Partial breast radiotherapy
4. Types of partial breast radiotherapy being studied
5. Types of partial breast radiotherapy being studied and offered at some BC Cancer Agency centres
6. Intensity-modulated radiation therapy (IMRT)
7. Potential contraindications for breast radiation
8. Side effects of radiation therapy

1. Recommendations for locoregional breast radiotherapy after breast conserving surgery

• Women who undergo BCS should be advised to have postoperative breast irradiation. Omission of radiation therapy after BCS increases the risk of local recurrence. Clear surgical margins are recommended prior to radiation
• A number of different fractionation schedules (i.e. the number of days over which a treatment is given) for breast irradiation are used and individualized to each patient. 50 Gy in 25 fractions (i.e. 25 treatment days) is equivalent to the 42.5 Gy in 16 fractions with regards to reducing the risk of local recurrence
• The BC Cancer Agency (BCCA) Breast Tumour Group recommends that patients with large breasts and those with significant post-operative induration, edema, erythema, hematoma or infection be offered whole breast extended fractionation with smaller daily doses over five to six weeks
• Additional irradiation to the lumpectomy site (boost irradiation) reduces local recurrence but can be associated with worse cosmesis compared with no boost. A boost following breast irradiation may be considered in women at higher risk of local recurrence, in younger women, and typically for those with close or positive margins after lumpectomy
• When choices are being made between different treatment options, patients must be made aware of the acute and late complications that can result from radiation therapy
• Breast irradiation should start as soon as the breast has healed from surgery (usually no sooner than three to four weeks) and ideally not later than 12 weeks after, except for patients in whom radiation therapy is preceded by chemotherapy. However, the optimal interval between BCS and the start of irradiation has not been defined
• The optimal sequencing of chemotherapy and breast irradiation is not clearly defined for patients who are also candidates for chemotherapy. Most centres favour the administration of chemotherapy before radiation therapy
• Patients should be offered the opportunity to participate in clinical trials whenever possible¹

Table 1. Radiation Treatment - Cross-sectional view
Cross-sectional view of a woman receiving radiation to the breast area. A: middle radiation beam B: side radiation beam C: bright yellow area indicates place where radiation is given to the breast D: rib cage/ chest wall E: heart F: lungs G: backbone H: sternum/ breast bone

Table content sourced with permission from www.breastcancer.org

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2. Recommendations for locoregional radiotherapy after mastectomy

Treatment decisions are individualized based on a number of factors.²

• Locoregional post-mastectomy radiation therapy (PMRT) is recommended for women with an advanced primary tumour:
  • 5 cm in size or greater;
  • that has invaded the skin, pectoral muscle or chest wall; or
  • where there is tumour present at the surgical or pathological margins after mastectomy, particularly if any of the following apply:
    • Age under 50
    • Lymphovascular invasion (LVI) positive
    • Grade 3, T2 tumour
    • T3 or T4 primary tumours
• PMRT is recommended for T1-2, N0, margin negative tumours in the following two settings:
  • Grade 3 and LVI positive
  • Grade 3 and T2 tumour (i.e. greater than 2 cm) and no systemic therapy used
• Locoregional PMRT is recommended for women with four or more positive axillary lymph nodes
  • Where the axillary nodes are involved, individualization of patient treatment is necessary. Indications for the use of regional radiotherapy include the presence of cancer in multiple or bulky lymph nodes or the presence of extranodal or extensive fatty involvement by cancer in the axilla
  • The role of PMRT in women with one to three positive axillary lymph nodes is still debated. However, results from existing clinical trials suggest a survival benefit and therefore, radiation oncologists should consider PMRT as an option for this patient group, discuss its risks and benefits, and individualize it to the patients circumstances
  • Other patient, tumour and treatment characteristics, including age, histologic grade, lymphovascular invasion, hormone receptor status, number of axillary nodes removed, axillary extracapsular extension and surgical margin status, may affect locoregional control and are considered in the deliberations on the utility of PMRT as discussed above
• PMRT may encompass some or all of the following regions: the chest wall and the supraclavicular, infraclavicular, internal mammary and axillary apical lymph node areas
• A definite recommendation regarding the inclusion of the internal mammary lymph nodes in PMRT cannot be made because of limited and inconsistent data
• The use of modern techniques in radiotherapy planning is recommended to minimize excessive normal tissue exposure, particularly to the cardiac and pulmonary structures
• Common short-term side effects of PMRT, including fatigue and skin erythema, are generally tolerable and not dose-limiting. Severe long-term side effects, including lymphedema, cardiac and pulmonary toxicities, brachial plexopathy, rib fractures and secondary neoplasms, are relatively rare
• The optimal sequencing of PMRT and systemic therapy is currently unclear. Herceptin can be administered concurrently with irradiation; however, additional caution is required in relation to cardiac volume and the inclusion of internal mammary nodes

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3. Partial breast radiotherapy

Whole Breast Radiation Therapy (WBRT) is the current standard for breast cancer treated with breast conserving surgery. It uses an external source of radiation to treat the whole breast every five days for five to six weeks. There is a 30-35% risk of local recurrence after BCS alone compared to 5-10% local recurrence after BCS and RT. As well, survival rates are improved by a few percent.

Despite the effectiveness of WBRT following breast conserving surgery, approximately 2-10% of women will develop a cancer recurrence in the same breast within 10 years of treatment.⁴ Local recurrence depends on a number of factors including the size and histology of the tumor, the woman’s age, the type of breast cancer, whether the axillary lymph nodes were involved, how close the surgical margins are, the time-interval after treatment, and whether a radiation boost was used during intital RT.

When there is a recurrence, 70-80% of the time it is close to the site of the original cancer (within 1 cm.).⁵ This suggests that the main value of WBRT is to prevent recurrence at the original cancer site and has raised the possibility that it may be effective to treat just that part of the breast initially involved by cancer rather than the whole breast. Treating just part of the breast is called Partial Breast RT (PBRT).

A number of different methods for delivering PBRT have been described and are currently being studied.⁵ The potential benefits of all of these techniques limit the exposure of healthy tissue to radiation and because a smaller volume is treated, the size of each radiation treatment can be larger. This means that PBRT can be completed in five to seven days instead of the three and a half to six weeks required for WBRT. Currently, however, whole breast radiation remains the standard of care. To be considered for PBRT trials, patients need to have smaller tumours and early stage disease.

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4. Types of partial breast radiotherapy being studied⁵

• Interstitial brachytherapy implants - Brachytherapy, also known as internal radiation, is another way to deliver radiation therapy. Instead of aiming radiation beams from outside the body, radioactive seeds or pellets are placed directly into the breast tissue next to the cancer. Radiation can be placed on a temporary or permanent basis
• Intracavitary brachytherapy - Consists of a balloon attached to a thin tube. The balloon is inserted into the lumpectomy space and filled with a salt water solution. A source of radioactivity is then temporarily placed into the balloon through the tube. The radioactive material is inserted and removed twice daily for five days. The balloon is then deflated and removed
• Intraoperative radiation (IORT) - A high dose of radiation is delivered to the tumour site during lumpectomy surgery. In some cases, no further radiation treatment is required following IORT, making it a much more convenient approach for delivering therapy. However, whether it is as effective as conventional whole breast irradiation has yet to be established. This procedure is not currently available in B.C.

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5. Types of partial breast radiotherapy being studied and offered at some BC Cancer Agency centres

Currently, interstitial brachytherapy implants (High Dose Rate Breast Brachytherapy) are being studied at Vancouver Island Centre and intraoperative radiation (IORT) at Vancouver Centre. See Open Clinical Trials for more information.

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6. Intensity-modulated radiation therapy (IMRT)

Intensity-modulated radiation therapy (IMRT) is a type of external beam radiotherapy that utilizes computer-controlled x-ray accelerators to deliver precise radiation to the area from which the tumour was removed. The radiation dose is designed to conform to the three-dimensional (3-D) shape of the biopsy cavity by modulating the intensity of the radiation beam to focus a higher radiation dose to the tumour bed while minimizing radiation exposure to surrounding normal tissues. Treatment is carefully planned using 3-D computed tomography (CT) images of the patient in conjunction with computerized dose calculations to determine the beam arrangement that will best conform to the tumour shape and minimize toxicity to the patient.⁵

Currently, IMRT is being studied in all four BC Cancer Agency centres. See Open Clinical Trials for more information.

7. Potential contraindications for breast radiotherapy

Radiation therapy may be relatively or absolutely contraindicated in the following circumstances, therefore a pre-operative discussion or consultation with a radiation oncologist is recommended:³

• Pregnancy
• Connective tissue disorders (S.L.E., scleroderma, etc.) with significant vasculitis
• Pacemaker in the treatment field (pacemaker may need to be moved)
• Prior radiation therapy to the same part
• Inability to abduct the ipsilateral arm 90 degrees
• Inability to comply with radiation treatments, such as attend appointments or lie still for treatments (e.g. dementia, movement disorders such as Parkinson's)
• Significant pre-existing lung disease particularly where the diffusing capacity is reduced
• Pre-existing pulmonary tuberculosis
• Cardiomyopathy

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8. Side effects of radiation therapy

See Radiation Therapy to learn about radiation side effects and how to minimize and manage them.

1. Clinical practice guidelines for the care and treatment of breast cancer, Guideline 6: Breast radiotherapy after breast-conserving surgery, Rev. Feb. 18, 2003, © 2006 CMA Media Inc. or its licensors.

2. Clinical practice guidelines for the care and treatment of breast cancer, Guideline 16: Locoregional post-mastectomy radiotherapy, Apr. 13, 2004, © 2006 CMA Media Inc. or its licensors.

3. BC Cancer Agency (http://www.bccancer.bc.ca). Vancouver (BC): 2006. (cited Sep 22, 2006). Available from: BC Cancer Agency's Cancer Management Guidelines -> Breast -> Management

4. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.234.

5. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.130.

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