**6. Management of metastatic disease in breast cancer**

Breast cancer can be in many cases, cured today, but around 20% of patients will experience recurrence in the first 10 years of follow-up. Late recurrence is possible and is depends on many factors such as biology and anatomic stage. Bone metastasis is the most common site of metastasis followed by lung, liver, and lymph nodes, in all breast cancer subtypes.

In advanced breast cancer, 60–80% of patients will develop bone metastasis [5]. Complications are mostly related to skeletal bone and refer mostly to pathological


*BC = breast cancer, i.v. = intravenous, MM = multiple myeloma, mo. = months, NS = Not significant, ONJ = Osteonecrosis of the jaw, AE = adverse effects, OS = Overall survival, pts. = patients, SRE = Skeletal-related* 

*events, wks. = weeks, y = years.*

**Table 2.** *Clinical trials of bisphosphonates in the metastatic setting.*

### *Perspective Chapter: Management of Bone Health in Breast Cancer Patients DOI: http://dx.doi.org/10.5772/intechopen.109030*

fractures, major surgery, radiotherapy, and spinal cord and nerve compression symptoms. This leads to loss of quality of life, pain, and increased health costs.

Hypercalcemia is, among others, a severe manifestation of metastatic disease or para-neoplastic events in breast cancer patients, related to high mortality risk. It is considered oncologic emergency requiring rapid evaluation and treatment.

Bone metastases are diagnosed through imaging, such as CT scan, MRI, PET-CT, and nuclear bone scans [26, 27]. A biopsy is usually required to confirm diagnosis and can help determine the immunohistochemical assay. Analysis of sampled bone biopsy needs more time because of preparation, which includes decalcification of the bone. Therefore, many oncologists will collect biopsies from different organs, e.g., liver, soft tissue, or lung. The receptor conversion rate (estrogen, progesterone and HER2 status) in bone metastases is much lower than in liver metastases. And this should be taken into consideration when deciding treatment options. For patients with breast cancer bone metastasis, this includes HER2-directed, endocrine-directed, and chemotherapy options.

Established as standard of care more than 20 years ago, bisphosphonates still remain a go-to drug for many oncologists in the daily clinical setting. Initial trials demonstrated reduction of skeletal-bone-related events, including, but not limited to, pain, as well as quality of life improvement for oncologic patients (See **Table 2**) [34–37].

Traditionally, standard application of zoledronic acid referred to dosing every 4 weeks, but newer trials showed that a deescalation to a 12 weekly based regime is as feasible and did not worsen outcome.
