How Is Secondary Breast Cancer In Bones Treated?

Breast cancer spreads to other organs in the last stage of cancer, which is an advanced stage. The metastasis (spread) may start as early as stage 3 cancer as cancerous cells are typically found in the regional lymph nodes by this stage.

When breast cancer targets bones as the site of invasion, it is known as secondary breast cancer is bones. In fact, the most common site for the breast cancer is bones. The bone metastasis deteriorates bones by decreasing its bone mineral density and consequently strength.

Is Stage 4 Cancer Treatable?

The final stage of breast cancer – stage 4 cancer, in which breast cancer spreads to bones is not curable, but treatable by your medical doctor. As the breast cancer has already progressed to advanced stage, it is difficult to completely eliminate the cancer.

The treatment for the breast cancer and bone metastasis can slow down or limit the extent of metastasis. Chiefly, the aim of intervention is to control the cancer growth and relieve the symptoms it causes. The goal of treatment varies with every stage of cancer, like to prevent metastasis, to slow down the growth, to cure the disease or to relieve the symptoms. So, the treatment goal should be clear.

The treatment options depends on a number of factors, these may include:

• Bone or bones that are affected
• Extent of weakening of bones
• Whether or not, there is any fracture
• Treatment in the past for the primary cancer
• Symptoms experienced by the patient
• General health of the patient

Types Of Treatment:

There are two main subsets of treatment for the breast cancer that has spread to bones. One is the local treatment that aims to treat the primary, and secondary sites of breast cancer. The other one is the systemic treatment which circulates in the whole body. Systemic treatment is necessary in the advanced stages of cancer to rule out the spread of cancer to any other organ and to prevent the recurrence of cancer. To treat bone metastasis in breast cancer, a combination of both  treatments is often used medical doctors.

Systemic Treatments:

Systemic treatments are very efficient to treat advanced stage breast cancer as they can reach every cancer cell throughout the body. Systemic treatments include chemotherapy, hormonal therapy or other medicines.

Bisphosphonates and radiopharmaceuticals are used as a treatment to specially treat bones and strengthen them. These treatments are specifically aimed at bone metastasis, although they cannot completely cure the disease.

• Chemotherapy:

As the name indicates, chemotherapy is the therapy done with the help of chemicals. In chemotherapy, drugs are used to kill the cancerous cells. The intake of these drugs can be through mouth or they may be injected into the vein.

After entering the body, these drugs travel through the bloodstream to reach every organ of the body. It destroys the cancerous cells from the breast and the bones to which they have metastasized. Another advantage of chemotherapy is that it may destroy the tumor cells in some other organs that is still not detected and doesn’t produce symptoms yet.

The biggest disadvantage of chemotherapy is that it affects the normal cells as well. This is the reason why patients undergoing chemotherapy lose weight and are often fatigued (cancer related fatigue).

• Hormonal Therapy:

Hormonal therapy is given to counterbalance the effects of some hormones. The drugs given in hormonal therapy block the receptor of specific hormones and consequently reduce the effect of that hormone. Breast cancer responds really well to the hormonal therapy due to the main role of estrogen hormone in the development of cancer.

Estrogen is the female hormone that is responsible for the development and growth of breast (other than the regulation of menstrual cycle and pregnancy, and also the development of other secondary features). However, an increase in estrogen hormone level causes increased growth of breast cells predisposing it for the cancer, while low level of estrogen has the opposite effects on the growth of breast cells.

Therefore, as the treatment of breast cancer, drugs that lower the estrogen levels or block its receptors (so it may not exert its effect) are given. When breast cells metastasize to bones, these drugs help to control the growth of cancer and cause shrinkage of the tumor.

• Targeted Therapy:

Target therapy aims at destroying specific parts of cancerous cells or certain proteins that help the tumor cells grow. This is beneficial in controlling the tumor growth by shrinking it. The drugs that are used in targeted therapy are different from the chemotherapy drugs. They can be used solely or combined with other treatments to successfully treat the secondary breast cancer in the bones.

• Immunotherapy:

The immune system is the body’s defense mechanism. A healthy and strong immune system saves the body from harmful agents by destroying them. Immunotherapy treats the secondary breast cancer by boosting the natural immune system or by producing artificial (man-made version of) immune system proteins. This helps in killing the misbehaving (tumor) cells, thereby treating bone metastasis.

• Radiopharmaceuticals:

Radiopharmaceuticals use radioactive drugs to treat the breast cancer and its metastasis. The use of radioactive drugs is preferred over using external radiation beams (radiotherapy) to treat cancer if it has spread to multiple bones.

The radioactive drugs are injected in the veins. Through blood, they reach the affected bones with greater osteoclastic activity (increased bone turnover). There, they incorporate and destroy the tumor cells by producing radioactive rays. The most common radioactive elements used are radium (Xofigo) and strontium (Metastron).

Radioactive drugs are helpful in eliminating the pain from bones for a vast period of time (several months). When the pain returns, the bones can again be targeted with the radiopharmaceuticals. However, the pain is not relieved for as long as with the first time treatment.

• Bisphosphonates:

Bisphosphonates are an additional treatment to reduce symptoms related to bones in secondary breast cancer. These drugs act on bones to reduce the osteoclastic activity (bone resorption) that is abnormally exaggerated in the breast cancer metastasis.

Osteoclasts are normal cells that are responsible for little bone resorption to remodel the bones in order to make them strong. However, it is the increased activity of osteoclasts in the breast cancer metastasis that is problematic.

Bisphosphonates help to treat the symptoms of secondary breast cancer by contributing the following:

• Reduced bone resorption that decreases the abnormally high blood calcium level seen in such patients.
• Limited bone weakening by controlling osteoclast activity. In turn, this decreases the chances of fractures.
• Decreased bone pain.
• Slowed down damage caused by cancerous cells.

The common side effects of bisphosphonates are fatigue, nausea, vomiting, fever, bone or joint pain and anemia. As they lower the calcium level in the blood, they shouldn’t be given to someone who already has low calcium in blood. They may also damage kidneys, therefore should be avoided in kidney compromised patients.

Local treatments:

Local treatments are directed at a specific part of body instead of targeting the entire body. Radiation therapy, surgery and ablation techniques are a few examples of local treatment regimens.

Local treatments are generally used when cancer is confined to a single bone or if the cancer has spread to multiple bones but there is one that is severely affected by the cancer and has an immediate need to treat. Also, it is used to stabilize a bone that is in danger of fracture as preventing the bone from fracture is easier than to treat it.

• Radiation Therapy:

Radiation therapy uses high energy rays to destroy the cancerous cells. It is beneficial if the cancer has affected just a few spots in the bone. In this procedure, external radiations are given from a machine and they are targeted to the affected bone.

To treat bone metastasis, the radiation therapy is given either in large doses (1 to 2 treatments) or in smaller amounts (5 to 10 treatments).

The main advantage of radiation therapy is that it can control the symptoms related to secondary breast cancer and relieves the pain. If the bones are treated before they weaken, it considerably decreases the risk of fractures.

• Ablation Techniques:

In ablation techniques, tumors are directly destroyed by putting the needle in them or by using cold, heat or chemicals. Ablation technique is restricted to the use only when one or two tumors are causing a problem.

One of the most common types of ablation techniques is radiofrequency ablation (RFA). In this procedure, patient is given general anesthesia so that he may not feel the pain. Then, a needle is inserted in the tumor with electric current at the tip of needle. The electric current basically heats the tumor till it gets destroyed.

Cryotherapy is another type of ablation techniques. It uses a cold probe that is inserted in the tumor. The extremely cold temperature of probe freezes the cancerous cells and they are destroyed. Other methods, like the use of alcohol, and other ways to change the temperature of cancerous cells (heat or freeze) are also used. After the treatment, the space is filled with the bone cement. It stabilizes, as well as strengthens, the bone.

• Surgery:

Surgery is done in order to relieve the symptoms and prevent the bone from fractures.  Breast cancer and bone metastasis can weaken the bones causing fractures.

As the healing of bones is difficult in these patients, it is imperative to prevent the fractures. Surgery can be done by inserting pins, needles, cages, plates and other devices. This helps the bones stabilize and fractures are prevented.

However, if the fracture has already occurred, surgery can be done to repair the bone and relieve the pain. Bone can also be fixed by using casts or splints if surgery can’t be performed due to the complications of cancer.

Conclusion:

Breast cancer may metastasize to the bones at the advanced stage. When multiple organs get affected by the cancer, it gets difficult to completely eliminate the cancer. However, several methods of treatment are available by your medical doctor to control the symptoms and relieve the pain. This drastically improves the quality of life of cancer patients.

References:

https://www.cancer.org/treatment/understanding-your-diagnosis/advanced-cancer/treating-bone-metastases.html

https://www.breastcancercare.org.uk/information-support/secondary-metastatic-breast-cancer/treatments-secondary-breast-cancer

http://www.breastcancer.org/treatment

https://www.webmd.com/breast-cancer/guide/breast-cancer-treatment#1