Lesion oxygenation associates with clinical outcomes in premalignant and early stage head and neck tumors treated on a phase 1 trial of photodynamic therapy.

BACKGROUND

We report on a Phase 1 trial of photodynamic therapy (PDT) for superficial head and neck (H&N) lesions. Due to known oxygen dependencies of PDT, translational measurements of lesion hemoglobin oxygen saturation (StO2) and blood volume (tHb) were studied for associations with patient outcomes.

METHODS

PDT with aminolevulinc acid (ALA) and escalating light doses was evaluated for high-grade dysplasia, carcinoma-in-situ, and microinvasive carcinomas of the H&N. Among 29 evaluable patients, most (18) had lesions of the tongue or floor of mouth (FOM). Disease was intact in 18 patients and present at surgical margins in 11 patients. In 26 patients, lesion StO2 and tHb was measured.

RESULTS

Local control (LC) at 24 months was 57.5% among all patients. In patients with tongue/FOM lesions LC was 42.7%, and it was 50.1% for those with intact lesions. Lesion tHb was not associated with 3-month complete response (CR), but StO2 was higher in patients with CR. In tongue/FOM lesions, baseline StO2 [mean(SE)] was 54(4)% in patients (n=12) with CR versus 23(8)% in patients (n=6) with local recurrence/persistence (p=0.01). Similarly, for intact disease, baseline StO2 was 54(3)% in patients (n=10) with CR versus 28(8)% in patients (n=5) without CR (p=0.03). In patients with intact disease, higher baseline StO2 associated with 24-month local control (p=0.02).

CONCLUSIONS

Measurement of the physiologic properties of target lesions may allow for identification of patients with the highest probability of benefiting from PDT. This provides opportunity for optimizing light delivery based on lesion characteristics and/or informing ongoing clinical decision-making in patients who would most benefit from PDT.