A standardized approach is crucial for the assessment of Neuropathic cancer Pain (NcP) in order to improve treatment results and clinical/pre-clinical studies, according to study results published in Pain.
While NcP is associated with specific therapy indications and worse treatment responses, data is lacking regarding the standardized clinical diagnosis of it. Consequently, study researchers sought to compare different clinical approaches to NcP assessment.
Patients (N=350) were recruited for a prospective cross-sectional study between May 2015 and June 2019 at the Palliative Care and Pain Outpatient Clinic at the National Cancer Center Institute of Milan. Participants were over 18 years old and had solid, locally advanced or metastatic tumors, were experiencing pain of at least 4 (on a 0 to10 scale) during the past 24 hours, and were receiving or needed to begin morphine, oxycodone, fentanyl, or buprenorphine. Patients were assessed for NcP by the Douleur Neuropathique 4 (DN4) questionnaire, clinical impression, and retrospective clinical classification.
Patients had a mean age of 63.4 years (standard deviation [SD], ±12.7 years). 54.9% were women, 93.7% had metastatic disease most commonly of the bone (55.7%) or lymph nodes (46.3%), and 68% were treated with antineoplastic therapy. In addition to opioids, about 87% were also receiving adjuvant drugs (steroids [43.7%], bisphosphonates [28.9%], anticonvulsants [28.6%], and non-steroidal anti-inflammatory drugs [13.4%]).
During the previous 24 hours, patients had pain of an average pain intensity of 5.4 (SD, ±1.4) and a maximum of 6.9 (SD, ±1.8). The patients reported experiencing pain for a mean of 12 months (interquartile range, 9). Pain had a bone component in 53% of patients, and 33% of patients reported visceral pain. Some patients had pain due to soft tissue damage (25%) and nervous tissue damage (20%).
The prevalence of pain among those diagnosed with NcP according to clinical impression compared with retrospective clinical classification was 36.9% (95% CI, 31.6%-42.1%) and 28.6% (95% CI, 23.8%-33.9%), respectively. The prevalence of pain among those diagnosed with the DN4 classification was 20% (95% CI, 15.9%-24.6%). Study researchers observed a moderate concordance between DN4 and retrospective clinical classification (k, 0.57; 95% CI, 0.47-0.67).
Localized pain was more commonly observed among patients with no NcP diagnosis. Pain only located in bone (45%) or visceral lesions (32%) was higher among those without NcP compared with those with NcP diagnoses (5% and 13%, respectively). Only 1 patient without an NcP diagnosis reported a combination of bone and nervous tissue damage, whereas 39% of patients with NcP reported pain due to a combination of bone and nervous tissue damage and 16% reported pain due to a combination of soft and nervous tissue damage.
This study was potentially limited by its large number of inclusion and exclusion criteria, making it unclear whether or not these findings may be applicable to a general population.
The study authors concluded that “the high heterogeneity of cancer pain makes a standardized approach for the assessment of NcP essential to improve the results of treatment and future clinical and pre-clinical studies.”
Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.
Shkodra M, Brunelli C, Zecca E, et al. Neuropathic pain: clinical classification and assessment in patients with pain due to cancer. Pain. Published online September 14, 2020. doi:10.1097/j.pain.0000000000002076