Secondary bone cancer indicates the spread, or metastasis, of a primary cancer from elsewhere in the body to the bones. Metastatic disease to bone or other sites represents an advanced stage of cancer, with fewer treatment options and generally poor prognosis. Symptoms of bone cancer include pain and fracture, and are often accompanied by nonspecific symptoms such as anorexia and weight loss.
Secondary Bone Cancer
A defining characteristic of cancer is its ability to spread and grow in other parts of the body, forming secondary tumors. These metastatic tumors can involve essentially any body site, but sites with higher blood flows, such as the lungs, liver and bones, predominate. Bone metastases most commonly arise from lung, breast and prostate cancers, along with thyroid, kidney and colon cancers, according to the Merck Manuals Online Medical Library. Early metastases are often asymptomatic, but as they grow and destroy the bone symptoms of pain, swelling or fractures appear. Plain X-rays and radionuclide scans of the entire skeleton detect bone cancers, and are often performed routinely as part of the work-up of a newly discovered cancer.
Weight Loss with Cancer
Weight loss frequently occurs in cancer patients with or without metastatic spread, and can be the first sign of the presence of cancer. Anorexia, or poor appetite, contributes to the risk of weight loss, compounded by the stress, anxiety and depression of a diagnosis of cancer. Treatment side effects such as nausea, vomiting, difficulty swallowing or sores in the mouth can lead to lower caloric intake, and metabolic changes often occur due to the cancer itself. All of these factors combined can lead to weight loss, more side effects from treatment and greater risk of other complications, according to the National Cancer Institute. Most cancer programs, therefore, put great emphasis on nutritional evaluation and therapy to help maintain body weight.
Direct Tumor Effects on Weight
Although poor appetite and eating difficulties contribute to weight loss in cancer patients, the tumors themselves can play a direct role. Anorexia is more common with large or extensive tumors, such as those with bone metastases, and can contribute to the development of cachexia. Cachexia is the medical term for loss of body fat and muscle protein seen in a variety of debilitating conditions including cancer. It is not entirely understood, but appears to be caused by a complicated mix of altered metabolism, chemicals directly released by the cancer and direct appetite suppression.
Approach to Weight Loss
Unfortunately, cachexia is the final cause of death in 20 to 40 percent of cancer patients, according to the National Cancer Institute. The best chance of reversing its progress is by successful treatment of the cancer, both at the original site and any secondary sites like bone. When this is not possible, nutritional therapy and efforts to improve a patient's appetite can help. Medications such as progestational agents or steroids to improve appetite and stimulate weight gain, better pain control, anti-nausea and anti-inflammatory drugs have all been used. Aggressive nutritional therapy can have some impact on cachexia, but often cannot totally reverse the associated weight loss.
