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Breast Cancer Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Stage I, II, IIIA, and Operable IIIC Breast Cancer

Table 6. Standard Adjuvant Chemotherapy Regimens for Stage I, II, IIIA, and Operable IIICHER2/neuNon-Overexpressing Breast Cancer continued...

Two additional randomized trials, though not specifically designed to address the timing of radiation therapy and adjuvant chemotherapy, do add useful information.[167,226] In the NSABP-B-15 trial, patients who had undergone breast-conserving surgery received either one course of CMF (n = 194) followed by radiation therapy followed by five additional cycles of CMF, or they received four cycles of AC (n = 199) followed by radiation therapy. No differences in DFS, distant DFS, and OS were observed between these two arms.[167][Level of evidence: 1iiA] The International Breast Cancer Study Group trials VI and VII also varied the timing of radiation therapy with CMF adjuvant chemotherapy.[226] These studies showed that delays from 2 to 7 months in radiation therapy after surgery had no effect on the rate of local recurrence.

Based on the above studies, delaying radiation therapy for several months after breast-conserving surgery until the completion of adjuvant chemotherapy does not appear to have a negative impact on overall outcome. Additionally, initiating chemotherapy soon after breast-conserving therapy may be preferable for patients at high risk of distant dissemination.

In an unplanned analysis of patients treated on a phase III trial evaluating the benefit of adding trastuzumab in HER2/neu-positive breast cancer patients, there was no associated increase in acute adverse events (AE) or frequency of cardiac events in patients who received concurrent adjuvant radiation therapy and trastuzumab.[227] Therefore, delivering radiation therapy concomitantly with trastuzumab appears to be safe and avoids additional delay in radiation therapy treatment initiation.

Timing of surgery

Several retrospective reviews have indicated that statistically significantly better DFS is achieved for premenopausal women with breast cancer and positive axillary lymph nodes if breast surgery is performed during the luteal phase (days 15–36) as compared with the follicular phase (days 0–14) of the menstrual cycle.[228,229,230][Level of evidence: 1iiA][231] Several other studies, however, have failed to support this finding or have found opposite results.[232,233,234,235][Level of evidence: 1iiA] Because of the inconsistent findings of these studies, it would be premature to mandate a modification in the scheduling of breast cancer operations according to the patient's menstrual cycle. A prospectively controlled trial (UCLA-9810046) has been completed but is not yet analyzed.

Chemotherapy risks

Adjuvant chemotherapy is associated with several well-characterized toxic effects that vary according to the individual drugs used in each regimen. Common toxic effects include nausea and vomiting, myelosuppression, alopecia, and mucositis. Less common, but serious, toxic effects include heart failure (if an anthracycline is used), thromboembolic events,[236] and premature menopause.[237] (Refer to the PDQ summary on Nausea and Vomiting and for information on mucositis, refer to the PDQ summary on Oral Complications of Chemotherapy and Head/Neck Radiation; for information on symptoms associated with premature menopause, refer to the PDQ summary on Fever, Sweats, and Hot Flashes.)

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