Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
When and How Should Radiotherapy Be Considered for Pain Management?
Introduction and Scope of the Problem
Patients with metastatic cancer can experience pain throughout their illness, whether it is due to the cancer itself or due to the effects of treatment such as surgical intervention, prior radiation therapy, or chemotherapy. It is estimated that approximately 30% to 50% of patients with cancer undergoing treatment experience pain, while 70% of patients with advanced cancer experience pain. When pain is directly related to the presence of tumor, radiation therapy is a reasonable treatment option for patients. Patients may experience pain either due to mass effect, nerve impingement, or the local destruction of soft or bony tissue. In these circumstances, palliative radiotherapy can provide effective treatment for about two-thirds of all patients, by directly shrinking the tumor and allowing the surrounding normal tissues to heal. Cancer pain is predominantly managed with pharmacological treatments, including opioid therapy, while the use of palliative radiotherapy is often delayed and underused. Specifically, for patients who can localize their sites of pain to one or a few areas that also correlate with radiographic findings confirming tumor, palliative radiation therapy may actually be preferable to initiating opioids by avoiding systemic pain medication side effects, such as constipation.
The utility of therapeutic radiation to shrink tumors and provide pain relief was noted within weeks of the discovery of X-ray technology in 1896. With modern advancements making treatment safer than ever before, currently half a million patients per year receive radiation at some point during their cancer treatment, and about one-third of all radiation treatments delivered are for palliative intent. Nevertheless, referrals for palliative radiotherapy, like those for hospice, are often made late—near death—when palliative radiotherapy becomes less effective as symptomatic tumors continue to destroy normal tissue. This may reflect a lack of knowledge on behalf of providers and a lack of integration with supportive care and pain management teams, although this is changing. There have been increasing developments of palliative radiation services in order to try to address this gap.
This chapter presents the rationale for the importance of frequent and early referrals to radiation oncology for pain management in the palliative care setting. The chapter briefly outlines how radiation therapy works, summarizes the benefits of a comprehensive radiation oncology evaluation, and provides an update on modern techniques that enable the safe delivery of radiation therapy with relatively few side effects. It also provides a practical overview of when physicians can refer to radiation oncology and what patients can expect.
Relevant Pathophysiology
Key Principles of Radiation Therapy
Bone Pain Due to Cancer
Patients with advanced cancer, particularly of the breast, prostate, or lung, may develop metastases in bones. For these patients, local destruction of bone, either by lytic (bone-destroying) or blastic (bone-forming) processes, can cause pain or catastrophic surgical emergencies and other skeletal-related events. Bone pain is initially caused by an activation in osteoclastic activity. Preclinical models have suggested that the local environment becomes acidic, thus activating pain receptors to create a dull, aching sensation, as described by the patient.
Untreated, bone metastases may result in the need for emergent surgery, prolonged hospitalization, a reduction in quality of life, and increased health care costs. Thus it is extremely important to assess the mechanical stability of the bone, particularly in high-risk areas. Classically, criteria used to discriminate high-risk bone metastases for fracture include Mirels’ criteria, which incorporates the location of the tumor, the severity of the pain, the degree of destruction, and whether or not the lesion is lytic or blastic. More modern data, however, suggest that this model is not robustly valid in a contemporary metastatic patient context. Newer approaches to assessing the benefit of orthopedic intervention include the open source PathFX tool, which uses machine learning to estimate the likelihood of survival after skeletal surgery for bone metastases. Ultimately, for patients who describe worsening pain with movement and weight bearing, orthopedic evaluation is likely indicated, and with appropriate orthopedic interventions and mechanical stabilization, pain can improve, sometimes immediately. Radiation therapy postoperatively is often indicated for both pain control and to ensure that the surgical hardware does not fail due to local progression of the disease.
Nerve Pain Due to Cancer
Patients with advanced cancer with tumors impinging on nerve roots or major nerve bundles may describe sensory changes or shocklike pain that corresponds to certain myotomes or dermatomes and to radiographic findings on scans. These tumors may directly compress the spinal cord or cauda equina , which are nerve roots exiting the neural foramina throughout the spine, or major nerve bundles such as the brachial plexus, lumbosacral plexus, or sciatic nerves, and can manifest a number of neuropathic pain syndromes.
For these patients, radiotherapy is not just a method of pain management but, with timely referral, can preserve neurological function.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here