Metastatic Breast Cancer: Bone Cancer

From the first moment my wife discovered she had breast cancer, there was a deafening silence from the men I know. Even ones whose wives, mothers or girlfriends had breast cancer seemed to have received a gag order from some Central Cancer Command and did little more than mumble about the experience. Not one to shut up for any known reason, I started this blog…

We just got news this week that a “cancer friend” of ours had a bone scan, and after an extended time of treatment, she is cancer free!

But just what IS bone cancer and why did she get it?

The cancer, while it can certainly occur by itself, is what is called metastatic breast cancer. It happens when cancer cells from the breast escape into the blood stream or the lymph system and invade MORE new flesh.

While bone cancer is the most common – 70% of metastatic breast cancers are of this ilk – the other 30% is made up of brain cancer (10%) and lymph, lung and liver cancer. Let me emphasize here that these cancers are NOT the peculiar type of cancer cells that initiate these diseases in people who have never had breast cancer. These cancers are BREAST CANCER cells that have invaded other organs and therefore are called metastatic breast cancer. The word “metastatic” was used in the 1570s and comes from the Greek metastasis which means "transference, removal, change.” The roots are meta which means "over, across" plus the word histanai which means "to place, cause to stand.” The medical use for "shift of disease from one part of the body to another" dates from 1660s in English.

Bone cancer caused by the invasion of breast cancer cells into the bones can first show up as back, bone, or joint pain lasting more than two to three weeks that seems to be getting worse; numbness or weakness in a particular part of the body; a change in bowel or bladder activity, such as problems with incontinence or not being able to urinate or have a bowel movement. This may be a sign that the nerves in your backbone are getting pinched by the cancer.

As well, blood tests can reveal a buildup of calcium or tumor markers (special proteins in the blood) like CEA (carcino-embryonic antigen), CA (cancer antigen) 15-3 or CA 27-29 that suggest the cancer might be in the bones. Calcium build up might also show up in a routine bone scan. These tests are NOT usual and are typically ordered only if the symptoms appear.

Metastatic bone disease (MBD) caused by invading breast cancer often behaves in a “mixed osteolytic (destroys bone cells) and osteoblastic (causes abnormal growth of bone cells) manner”. Bone destroying or bone growing MBD occurs because the different cancer cells give off chemicals that interfere with the naturally occurring cells in the bone and cause bone destruction, new bone formation, or both. MBD weakens the affected bones, people with the disease are prone to fractures. Broken bones caused by MBD are termed "pathological fractures."

The most common treatment options for MBD include radiation and medications to control pain and prevent further spread of the disease, and surgery to stabilize bone that is weak or broken. By killing the cancer cells, radiation relieves pain, stops the tumor from growing and can prevent the bone from breaking. Radiation can also be used to control the cancer after surgery to fix a broken bone.
MBD is a systemic (body-wide) problem and radiation therapy may be use just to lessen symptoms and pain in more advanced cases, or to completely destroy disease in the affected bone.

Different cancers respond differently to radiation. Several types of radiation therapy are available. Local field radiation is the most common type of radiation used to treat MBD in which radiation is directed at the metastatic tumor and the immediate adjacent tissue. Entire bone segments or multiple bones can be targeted by local field radiation, depending upon how many areas are affected by the disease. This usually results in complete pain relief in 50% to 60% of cases and partial relief in more than 80% of cases. How well MBD responds to radiation depends on many things, including cancer type (for example, breast cancer typically responds very well to radiation, while kidney cancer does not), and where the tumor is located.
Pain usually begins to subside in the first 1 to 2 weeks, but maximum relief may take several months. Therefore, pain medication is prescribed throughout the radiation treatment course.

For our “cancer friend”, the treatment has been effective and with the pain greatly reduced, we are planning to actually meet for the very first time for dinner over the holiday season!

References: http://www.breastcancer.org/symptoms/types/recur_metast/where_recur/local.jsp , http://orthoinfo.aaos.org/topic.cfm?topic=A00093

Image: http://www.meddean.luc.edu/lumen/meded/Radio/curriculum/Harrisons/Oncology/mets5b.jpg