Radiomodulation in Mixed, Complex Cancer Pain by Triple Target Irradiation in the Brain: A Preliminary Experience

Hypophysectomy, pituitary neuroadenolysis and pituitary radiosurgery for the treatment of refractory cancer pain: a historical review and mechanism investigation

Refractory cancer pain affects 10-20% of patients with advanced malignancies and is not adequately controlled by opioids. The intrathecal therapy is an effective interventional procedure for referral, but the implanted infusion pumps are costly and the refilling requires technical expertise. Hypophysectomy, in its three stages-surgical, chemical, and radiosurgical-has emerged as an alternative for managing this pain. However, the underlying mechanism remains elusive, with existing hypotheses unable to comprehensively account for both the initial and long-term analgesic effects. This literature review explores the historical evolution, clinical outcomes, and hypothesized mechanisms of hypophysectomy for pain relief. Surgical hypophysectomy initially demonstrated an 85.5% success rate but carried significant risks like diabetes insipidus and hypopituitarism. Chemical hypophysectomy reduced invasiveness, achieving 75.1% pain relief with fewer complications. Modern pituitary radiosurgery has improved safety while maintaining high efficacy (initial relief: 95.9%, long-term: 73.5%). The mechanisms underlying pain relief remain unclear but include tumor regression, increased β-endorphins, neuroendocrine modulation, and hypothalamic involvement. A new hypothesis suggests that radiosurgery induces hormone redistribution (e.g., oxytocin, vasopressin) through hypothalamic-pituitary modulation, contributing to both immediate and long-term analgesia. Despite its potential, unresolved issues such as optimal radiation dose, pain assessment standardization, and precise mechanisms limit widespread adoption. This review underscores the need for larger, homogenous studies to validate the safety and efficacy of hypophysectomy in treating refractory cancer pain. These findings offer a promising avenue for improving palliative care in oncology.

Everything old is new again. revisiting hypophysectomy for the treatment of refractory cancer-related pain: a systematic review

Cancer-related pain is a common and debilitating condition that can significantly affect the quality of life of patients. Opioids, NSAIDs, and antidepressants are among the first-line therapies, but their efficacy is limited or their use can be restricted due to serious side effects. Neuromodulation and lesioning techniques have also proven to be a valuable instrument for managing refractory pain. For patients who have exhausted all standard treatment options, hypophysectomy may be an effective alternative treatment. We conducted a comprehensive systematic review of the available literature on PubMed and Scielo databases on using hypophysectomy to treat refractory cancer-related pain. Data extraction from included studies included study design, treatment model, number of treated patients, sex, age, Karnofsky Performance Status (KPS) score, primary cancer site, lead time from diagnosis to treatment, alcohol injection volume, treatment data, and clinical outcomes. Statistical analysis was reported using counts (N, %) and means (range). The study included data from 735 patients from 24 papers treated with hypophysectomy for refractory cancer-related pain. 329 cancer-related pain patients were treated with NALP, 216 with TSS, 66 with RF, 55 with Y90 brachytherapy, 51 with Gamma Knife radiosurgery (GK), and 18 with cryoablation. The median age was 58.5 years. The average follow-up time was 8.97 months. Good pain relief was observed in 557 out of 735 patients, with complete pain relief in 108 out of 268 patients. Pain improvement onset was observed 24 h after TSS, a few days after NALP or cryoablation, and a few days to 4 weeks after GK. Complications varied among treatment modalities, with diabetes insipidus (DI) being the most common complication. Although mostly forgotten in modern neurosurgical practice, hypophysectomy is an attractive option for treating refractory cancer-related pain after failure of traditional therapies. Radiosurgery is a promising treatment modality due to its high success rate and reduced risk of complications.

Dual-Target Radiosurgery for Concomitant Continuous Pain Presentation of Trigeminal Neuralgia: Radiomodulation Effect and Dose

OBJECTIVES

Patients with trigeminal neuralgia (TN) experience concomitant continuous pain (CCP) that can be difficult to treat. A dual-target approach delivering a high dose of radiation to the nerve and the contralateral thalamus can develop a fast radiomodulation effect on lowering pain. We sought to determine if this effect was dose dependent.

METHODS

We retrospectively reviewed 21 patients treated with radiosurgery in CCP and severe TN pain, with a visual analog scale (VAS) score of nine out of 10 at the time of treatment. Ten patients were treated with a high dose (>120 Gy) in the thalamus 90 Gy to the nerve, and the rest with a low dose (<120 Gy) to the thalamus and >90 Gy to the nerve.

RESULTS

Of those who received the high dose to the thalamus, six patients (60%) received 140 Gy, and four (40%) received 120 Gy, with a median dose to the trigeminal nerve of 90 and 85 Gy, respectively. The high thalamus dose showed a radiomodulation effect from day 1. The low thalamus dose did not produce radiomodulation on any of the first four days. The percentage of VAS score reduction one month after treatment was higher in the high-thalamus dose group than in the low-thalamus dose group. At three months, VAS score was 2 in the high-dose group and 4 in the low-dose group.

CONCLUSIONS

The radiomodulation effect in pain and dual-target radiosurgery is dose dependent in CCP in TN; a high dose can provide a more consistent clinical result than a lower dose.

Novel single nucleotide polymorphism biomarkers to predict opioid effects for cancer pain

There have been few studies on predictive biomarkers that may be useful to select the most suitable opioids to optimize therapeutic efficacy in individual patients with cancer pain. We recently investigated the efficacy of morphine and oxycodone using single nucleotide polymorphisms (SNPs) of the catechol-O-methyltransferase (COMT) rs4680 gene as a biomarker (RELIEF study). To explore additional biomarkers that may enable the selection of an appropriate opioid for individual patients with cancer pain, three SNPs were examined: C-C motif chemokine ligand 11 (CCL11; rs17809012), histamine N-methyltransferase (HNMT; rs1050891) and transient receptor potential V1 (TRPV1; rs222749), which were screened from 74 pain-related SNPs. These SNPs, which were identified as being significantly associated with the analgesic effect of morphine, were then used to genotype the 135 patients in the RELIEF study who had been randomized into a morphine group (n=69) or an oxycodone group (n=66). The present study then assessed whether the SNPs could also be used as selective biomarkers to predict which opioid(s) might be the most suitable to provide pain relief for patients with cancer. Oxycodone tended to provide superior analgesic effects over morphine in patients carrying the genotype AA for the CCL11 rs17809012 SNP (P=0.012 for interaction), suggesting that it could serve as a potential biomarker for personalized analgesic therapy for patients suffering with cancer pain.