Can breast cancer be treated?

Yes, it can be treated.

Breast cancer is usually treated with surgery and then possibly with chemotherapy or radiation, or both. Hormone positive cancers are treated with long term hormone blocking therapy. Treatments are given with increasing aggressiveness according to the prognosis and risk of recurrence.

• Stage 1 cancers  have an excellent prognosis and are generally treated with lumpectomy and sometimes radiation. Cancers should be treated with the trastuzumab regime.Chemotherapy is uncommon for other types of stage 1 cancers.
• Stage 2 and 3 cancers with a progressively poorer prognosis and greater risk of recurrence are generally treated with surgery (lumpectomy or mastectomy with or without lymph node removal), chemotherapy and sometimes radiation (particularly following large cancers, multiple positive nodes or lumpectomy).
• Stage 4, metastatic cancer, (i.e. spread to distant sites) has poor prognosis and is managed by various combination of all treatments from surgery, radiation, chemotherapy and targeted therapies. 10 year survival rate is 5% without treatment and 10% with optimal treatment.
• Planning Your Treatment 
  What types of treatment are available and which might be appropriate for you.
  Surgery
  Breast-conserving surgery (lumpectomy), mastectomy, and lymph node dissection, and what to expect from each.
  Chemotherapy
  Who should get it, how it works, different types, side effects, and how to manage them.
  Radiation Therapy
  What it is, who it's for, advantages, side effects, and what to expect when you get it.
  Hormonal Therapy
  The link between hormones and breast cancer and how different groups of drugs — including ERDs, SERMs, and aromatase inhibitors — can affect that link.
  Targeted Therapies
  Including Herceptin: How they work, who should get them, how they're given, side effects, and major studies.