Radiotherapist, René Botha, educates us on how bone metastases form, the common symptoms and treatment options.
Bone metastases, or ‘bone mets’, are common secondary tumours in cancer patients. Therefore, it’s crucial to understand the causes, common symptoms, diagnosis and treatment options.
Causes of bone metastases
Bone mets are different to primary bone cancers, which begin in the bone itself and are relatively rare. Bone mets occur when a primary cancer which started elsewhere in the body spreads via the blood to the bone.
Types of bone mets
When cancer spreads to the bone, it causes changes within the bone. There are two types of bone mets and patients may have both at the same time.
Osteolytic mets are more common and occur when the cancer cells break down parts of the bone and form ‘holes’ which weaken the bone.
Osteoblastic mets develop when the cancer cells cause excess bone to form, making the bones very dense, but that doesn’t mean stronger.
Many cancers may spread to bone. However, the most common include breast-, prostate- and lung cancer.
Symptoms
Pain is the most common symptom, and it varies depending on the location of the met. It’s usually persistent and gradually increases over time becoming more severe.
Some patients experience fractures or broken bones due to the metastatic lesions weakening the bone. The risk of this occurring is higher in weight-bearing bones. While patients should be aware of the risk of fractures, not all bones will break. Some treatments are given to reduce the risk of fracture.
Vertebral body mets sometimes result in spinal cord compression, when the tumour or weakened bone puts pressure on the spinal cord.
The symptoms suggestive of this may include severe pain, urinary and/or bowel incontinence, weakness of the arms and/or legs and sensory changes corresponding to the level of the compression. A patient who experiences any of these symptoms should report them to their doctor urgently.
As the bones break down, higher levels of calcium are released into the blood and this may cause nausea, vomiting, constipation and confusion.
Diagnosis of bone mets
Several investigations may be requested, depending on the patient’s specific symptoms, to identify if there are mets. These investigations may include blood tests, X-rays, a bone scan, a CT and/or MRI scan, a PET scan or a bone biopsy.
Treatment of bone mets
The aim of treatment is to reduce skeletal related events, such as fractures, and to manage pain to improve quality of life.
- Bone-strengthening medications are sometimes used to reduce pain, the risk of fracture and prevent new metastases from forming.
- Pain management is an important aspect of treatment and the best combination of medications should be found for each patient.
- Depending on the primary cancer, systemic therapies may also be used in an attempt at controlling the bone mets for as long as possible, such as chemotherapy, targeted therapy and hormonal therapy.
- Occasionally surgery is needed to repair fractured bones or stabilise bones in danger of breaking.
- Radiotherapy may also be used to reduce pain and in cases of spinal cord compression. This is done using external beam radiotherapy to limited areas. In some cases, a radiopharmaceutical may be injected intravenously to treat multiple bone metastases.
- Steroids, used cautiously, can assist in pain management as they reduce inflammation and swelling around the cancer sites.
- Physiotherapy may be used to improve strength and range of motion.
It’s vital to remember that not all pain means mets. If a patient is concerned about symptoms, these should be discussed with the treating doctor for appropriate management. Patients with bone mets may live for years and still maintain a good quality of life.
References:
- Coleman R, Hadji p, et al. Bone health in cancer: ESMO Clinical Practice Guidelines. Ann Oncol. 2020 Dec; 31(12): 1650-1663
- Bone metastasis: Symptoms, treatment, outlook, and more (medicalnewstoday.com) accessed on 27 February 2021
- Bone Metastases (cancer.org) accessed on 27 February 2021
- Cancer Spread to Bones: Life Expectancy, Treatment, Types (healthline.com) accessed on 27 February 2021
MEET OUR EXPERT – René Botha
René Botha is a radiotherapist with a special interest in treatment planning. She works in private practice and is based at the Wits University Donald Gordon Medical Centre.