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Back pain in men with prostate cancer and spinal metastasis is often assumed to be cancer-related, but other causes come into play more often than you might think, a new study found.

"Underconsidered, underappreciated, and at times incompletely addressed in oncologic practice and in the eligibility criteria for clinical trials are the nonmalignant causes of back pain that are frequently present in the age group at which prostate cancers are typically diagnosed," said Lisa Marie Ruppert, MD, of Memorial Sloan Kettering Cancer Center in New York City, and colleagues.

"Failure to accurately attribute causality of pain and/or neurologic symptoms may lead to overtreatment, exposure to unnecessary side effects from cancer-directed therapy and/or analgesics, and a failure to ameliorate symptoms, leading to further functional compromise," Ruppert's group wrote in

For the study, the team retrospectively reviewed assessments of back pain conducted by a specialist in 53 men with prostate cancer and spinal metastasis who were evaluated at a pilot joint oncology-physiatry clinic. All the men had pain at the site of metastasis. Surprisingly, however, the pain was either fully or partially attributable to non-malignant causes in 33 (62%) of the patients.

"This retrospective review highlights the prevalence of non–cancer-related spine pain in men with metastatic prostate cancer, which will not respond to tumor-directed therapies, but rather to rehabilitation-driven efforts guided by a shared care model," the authors concluded.

In the following interview, Ruppert, who is associate director of the Cancer Rehabilitation Medicine Fellowship Program, discussed additional findings and implications of the study, as well as approaches for managing back pain.

The patients in this study were evaluated at a pilot joint oncology-physiatry clinic. Please tell us about the objectives of this clinic and how it works.

Ruppert: Back pain is common, and low back pain is a leading cause of disability worldwide. From a medical oncologist's perspective, evaluating back pain in a prostate cancer clinic typically triggers concerns and investigations related to metastatic bone disease.

These investigations are because bone, particularly the spine, is the most common site of metastatic prostate cancer spread -- 90% -- and, beyond pain, can be a harbinger of severe neurological compromise. However, this runs the risk of incompletely considering non-malignant causes of back pain that might be present in the age group at which prostate cancers are typically diagnosed in oncology practice and focused on in clinical trials.

These non-malignant causes can compromise patient functionality and adversely affect quality of life. Physiatrists specialize in neurologic and musculoskeletal impairments and can provide pain relief recommendations and maximize function for individuals with back pain.

Genitourinary Medical Oncology and Physiatry formed a partnership to bring joint expertise to individual patient management at our center in a newly created, co-located, inter-disciplinary clinic that facilitated same-day cross-referrals to each specialist. Patients for whom a malignant cause seemed less likely were referred for same-day physiatry assessment. These collaborative clinical assessments allowed for real-time clinical discussions between providers, more streamlined investigations, patient-centered rehabilitation intervention investigations and medication management, and alignment of care objectives.

Strikingly, in our retrospective assessment of this Collaborative Spinal Pain Clinic, 62% (n=33/53) of men with advanced prostate cancer evaluated had a non-malignant contributor to their pain assessed and addressed by physiatry. We believe the efficiency and agility of this joint care clinic model led to enriched patient care and clinical learning.

This study was, we acknowledge, limited as a retrospective review of a small sample size that included referral bias but has served to highlight an area of need for patients with metastatic prostate cancer, meriting further optimization.

Our Collaborative Spinal Pain Clinic is expanding its focus to assess outcomes of recommended intervention through prospective trials using patient-reported outcome tools and standardized clinical assessments. Our goal is to fully understand the role that non-cancer comorbidities play in the physical functionality and quality of life throughout a patient's disease.

What were some of the sources of non-malignant pain found in your study?

Ruppert: In this study, causes of non-malignant pain etiologies included lumbar stenosis, lumbar degenerative disc disease, and cervical and lumbar spondylosis.

Did you find any features of a patient's clinical history that tended to suggest a non-cancer etiology for their back pain?

Ruppert: While evaluating back pain symptoms, providers inquired about a pre-cancer history of back pain, the description of pain, and interventional procedures, including surgery performed for management. Pre-cancer symptoms enabled us to compare their current symptoms to previous ones during physiatry evaluation. Here, essential features included the timing of pain onset in relation to current disease status; changes in oncologic therapies; and response to cancer treatments, medications, and interventions trialed, which provided insight into possible etiology.

Pain symptoms similar to those diagnosed prior to cancer and no change with cancer treatment raised the possibility of a non-cancer cause, as did reports of activity-related pain, a description common in those with degenerative changes in the spine.

Interestingly, activity-related pain was the most frequently described pain type in 42% of our cohort. Reports of biologic pain, a pain related to periosteal stretching and inflammation from tumor growth, would raise concerns for cancer-related causes.

Physical examination findings such as postural abnormalities and decreased spine range of motion raised concerns about the competence of the vertebral bodies, intervertebral discs, and spine kinematics. Spinal imaging confirmed the presence, location, and extent of both metastatic lesions and degenerative spine changes. These clinical findings assisted in diagnosing non-cancer contributions to pain.

What approach does the physiatrist at your clinic use to manage back pain?

Ruppert: The physiatrist at our clinic focuses on pain alleviation, prevention, improving functional status, and overall quality of life. Rehabilitation interventions are patient-tailored and include physical therapy, recommendations on independent exercise, postural bracing, and medications when indicated. It is essential to highlight that no new opioids were prescribed in our study.

These rehabilitation interventions focus on core muscle engagement, strengthening spine extensor muscles, improving proprioception around joints, and correcting posture to offload spinal column structures. The physiatrist provides appropriate precautions for movement and lifting to prevent injury and ensure safety with activities.

What is your advice for oncologists based on the results of this study?

Ruppert: Non-cancer-related spine pain is prevalent in men with metastatic prostate cancer. This pain will not respond to tumor-directed therapies but rather to rehabilitation-driven efforts.

A joint clinic model can lead to a rich collaboration between medical oncology and physiatry to help orient management around interventions that more optimally encompass a strategy to treat cancer, diminish pain, increase activity levels, and improve quality of life.

Read the study here.