Mastectomy refers to an operation to remove one or both breasts. The most common indications for mastectomy include:

• Patients with large, malignant or centrally located tumours may undergo mastectomy. If there are inadequate margins around the primary tumour and a breast is too small for a more extensive removal to be performed, mastectomy is recommended.
• Multicentric carcinoma is a locally recurring cancer after a breast conserving surgery. Mastectomy is indicated when there are new primary tumours after previous breast conserving surgery.
• If the breast conserving surgery is found to be inadequate in controlling or removing the tumor, a mastectomy may be undertaken.
• In patients with extensive carcinoma in situ after breast conserving surgery, there is an unacceptably high risk of invasive carcinoma developing and a mastectomy is indicated.
• Prophylactic mastectomy – Some patients who have a high risk of malignancy due to a strong family history of breast cancer or mutations in the BRCA1 or BRCA2 genes, may opt for a prophylactic mastectomy to remove the breasts before cancer forms.
• Sometimes, patients may prefer to avoid post-surgery radiotherapy to the breast. This is common among patients who have previously failed wide excision and radiation treatment in the opposite breast.
• Contralateral mastectomy is removal of the opposite breast. This could be performed if a woman does not want one large breast to remain after surgery or to reduce the risk of further cancer developing in it.

From a surgical point of view, an ideal mastectomy case is a young, thin and fit patient with a small tumor and a small breast, while obese and large-breasted women who have had previous breast radiation therapy or surgery represent difficult cases. Women with previous breast augmentation or breast reduction surgeries are also difficult cases.

Women with inflammatory carcinoma, extensive metastasis or distant spread of the cancer are unsuitable for this surgery.