256 - BEYOND PAIN SCORES: PHOTOBIOMODULATION REDUCES ANALGESIC BURDEN AND IMPROVES TREATMENT TOLERANCE DURING CHEMORADIOTHERAPY FOR ORAL CAVITY CANCER

Purpose/Objective(s):

Escalating analgesic use is a major consequence of radiation-induced oral mucositis (RIOM) in patients undergoing chemoradiotherapy (CRT) for oral cavity squamous cell carcinoma (OCSCC), often driving opioid escalation and contributing to unplanned treatment interruptions. Photobiomodulation (PBM) has demonstrated anti-inflammatory and analgesic effects, but its role in reducing analgesic burden during CRT remains under-evaluated in OCSCC. We hypothesised that PBM would reduce analgesic escalation and improve treatment continuity in this setting.

Materials/Methods: Eighty-two patients with histologically confirmed OCSCC planned for adjuvant or radical CRT (60–70 Gy; concurrent cisplatin) were randomised into two groups: PBM with standard supportive care (n=41) and standard supportive care alone (n=41). PBM was initiated after the appearance of RTOG Grade 2 mucositis and delivered five days per week until completion of radiotherapy. Analgesic requirement was graded weekly using the WHO analgesic ladder. Pain intensity was assessed weekly using Visual Analogue Scale. Treatment interruptions were documented.

Results: Pain scores were comparable between groups during weeks 1 and 2. From week 3 onwards, the PBM group demonstrated significantly lower pain scores compared to controls at weeks 3 (3.59±0.95 vs 4.32±1.08; p=0.002), week 4 (4.37±1.18 vs 4.88±1.20; p=0.046), week 6 (5.28±1.20 vs 5.97±1.05; p=0.01), and week 7 (5.52±1.33 vs 6.76±1.48; p=0.016). Analgesic requirements were significantly lower in the PBM group across most weeks, with reduced WHO step escalation from week 2 to week 7 (p<0.05). Radiotherapy interruptions were fewer in the PBM group (12.2% vs 29.3%), although this did not reach statistical significance (p=0.057).

Conclusion: Mean WHO analgesic ladder scores were significantly lower in the PBM group across weeks 2–6 (all p<0.05; Table 1), reflecting reduced need for opioids throughout treatment. By week 7, the PBM arm maintained a mean ladder score of 1.90 vs 2.29 in controls (p=0.091), indicating that control patients were approaching strong opioid requirement. Notably, only 2 patients (4.9%) in the PBM arm required Grade 3 (strong opioid) analgesics, compared to 6 patients (14.6%) in the control arm. Pain scores were significantly lower in the PBM group from week 3 onwards (weeks 3, 4, 6, and 7; all p<0.05). Radiotherapy interruptions were fewer in the PBM arm (12.2% vs 29.3%; p=0.057).

Table 1. Weekly mean WHO analgesic ladder scores: PBM group vs control group

	Test Group		Control Group
	Patients studied	Mean + SD	Patients studied	Mean + SD	p-value
Week 2	39	0.08 + 0.27	41	0.29 + 0.46	0.014^
Week 3	39	0.44 + 0.50	41	1.02 + 0.47	<0.001^
Week 4	39	1.08 + 0.58	40	1.55 + 0.60	0.001^
Week 5	39	1.36 + 0.58	39	1.87 + 0.34	<0.001^
Week 6	39	1.77 + 0.54	37	2.03 + 0.50	0.034^
Week 7	20	1.90 + 0.55	17	2.29 + 0.59	0.091^