Predicting patients at risk for pain associated with electrochemotherapy

Electrochemotherapy describes the use of electric pulses to enhance chemotherapy uptake, and has proven highly efficient in treating cutaneous metastases. Patients referred for electrochemotherapy present with diverse clinical pictures, from multiple small lesions to large, ulcerated lesions. Post-electrochemotherapy pain has been observed in some patients. The objectives of this study were to evaluate pain scores before and after electrochemotherapy, and to investigate if patients at risk of post-procedure pain could be identified.

Seven cancer centres in the International Network for Sharing Practices on Electrochemotherapy (INSPECT) consecutively and prospectively reported to a common database. Electrochemotherapy consisted of intratumoural or intravenous injection of bleomycin, followed by delivery of electric pulses in local or general anesthesia.

Of 121 patients 39% had metastatic melanoma, 18% squamous cell carcinoma, 16% breast cancer, 13% basal-cell carcinoma, and 14% other malignancies. Median size of the largest nodules was 2.3 cm (range 0.3-40 cm). A majority of patients presented with low pain scores, and this continued through follow-up (74%). A subset of patients had moderate (13%) or severe pain (13%) after treatment. Post-procedure pain was statistically significantly associated with: 1) moderate or severe pain before treatment (p<0.0001); 2) size of the largest treated lesion (p<0.01); 3) previous irradiation (p<0.02); and 4) high treatment current value (p<0.0001).

The majority of patients had no or mild pain after electrochemotherapy. Patients at risk for post-procedure pain could be identified at the pre-treatment visit, and/or at the time of treatment, enabling a pain management strategy for this group.