Locoregional recurrence may follow modified radical mastectomy or partial mastectomy. Locoregional recurrence following modified radical mastectomy carries a poor prognosis but approximately 15% of patients will be long-term survivors after further locoregional therapy. Recurrence in the breast following partial mastectomy is curable with much greater probability. The survival of patients under these circumstances is parallel to that of patients with new tumours of similar stage.

Tumours should be carefully assessed, as some of these in-breast 'recurrences' are not recurrences but new primary breast cancers, which may require different treatment and may give a different prognosis. (e.g. the new tumour may be ER+ and the initial tumour ER-). All patients should have a biopsy to confirm recurrent disease and to assess biomarker status.

A proportion of these patients will already have demonstrable metastatic disease and a full metastatic work-up should be performed. This should include a mammogram of the contralateral breast as well as a CBC, liver enzymes, CA15-3, bone scan and chest x-ray.

The patient may be referred to BC Cancer for an opinion from the multi-disciplinary group at the Breast Conference.

If the recurrence is solitary, wide local excision is advised if possible. If the recurrence is in the axilla and the patient has not previously had an axillary node dissection, then an axillary node dissection should be considered.

If the patient has not had previous radiation therapy, then radiation therapy should be given to the chest wall and the lymph node bearing areas with appropriate dose build-up at the site of the recurrence after it has been excised.

At present there is no defined role for chemotherapy under these circumstances, but it should be discussed in patients who have never received adjuvant systemic therapy and are otherwise well.

Tamoxifen has been demonstrated to delay recurrence, but a statistically significant improvement in survival has not been demonstrated in randomized trials. If the initial tumour or the recurrent lesion is hormone receptor positive or unknown then an appropriate hormonal manoeuvre should be considered. This will usually be with an aromatase inhibitor or tamoxifen 20 mg po daily for five years or longer, depending on which hormone therapy was used in the initial adjuvant setting and the menopausal setting of the patient. For premenopausal women, there should be consideration of ovarian ablation by surgery or radiation therapy. Extrapolating from the adjuvant and metastatic setting, first line aromatase inhibitors are superior to tamoxifen in terms of time to disease progression and are therefore an appropriate first line option for post-menopausal patients in this setting.

Patients who did not undergo radiation to the breast after initial partial mastectomy are more likely to experience a local recurrence. If these patients are prepared to accept radiotherapy on recurrence, breast conservation is still possible and a repeat local excision can be carried out followed by radiation therapy to the residual breast tissue. Mastectomy is usually recommended for patients without demonstrable metastases if the patient has had prior breast radiotherapy. In both circumstances, the cure rate will approach that of primary surgery on a similar lesion. Axillary surgery should be performed as appropriate, based on what previous axillary surgery the patient has had and the clinical status of the axilla at the time of recurrence. 

If the breast/chest wall has been previously irradiated, usually re-irradiation is not advised. If the breast/chest wall has not previously been irradiated, then radiotherapy should be delivered to the breast/chest wall. If the recurrence is in the axilla or supraclavicular fossa and these lymph node areas have not previously been irradiated, then radical radiation therapy should be delivered to the axilla and supraclavicular node areas. 

Data supports the use of aggressive locoregional and systemic management for the highest likelihood of cure in patients who develop an isolated in-breast, chest wall, or axillary recurrence that is resectable. Chemotherapy in this setting has been shown to increase survival and cure rates.²⁷ The choice of chemotherapy depends on patient factors, prior therapy given, and time elapsed since prior adjuvant therapy.

If the recurrence is in the axilla, if lymphatic or vascular invasion is identified, or if the invasive tumour is > 2 cm + any grade or >1 cm + grade III, then adjuvant chemotherapy and/or hormone therapy may be considered, depending upon the patient's health status and age, history of prior adjuvant treatment, and estrogen receptor status. Referral to a medical oncologist is encouraged.