CHICAGOThe degree of oxygenation of malignancies in the neck may indicate which patients with squamous cell carcinoma should receive adjuvant therapy, according to a study conducted at Duke University Medical Center.
The study revealed a highly significant difference in pretreatment tumor oxygenation status among patients who were pathologically negative and those who had positive tissue evidence of carcinoma at surgery.
Patients with tumor hypoxia had nearly an eightfold increase in the likelihood of residual disease at the time of neck dissection, David M. Brizel, MD, reported at the Second International Chicago Symposium on Malignancies of the Chest and Head & Neck. Hypoxia was an independent predictor of residual disease after the delivery of radiation, which fits with the concept of hypoxia-mediated radioresistance (see also "Hypoxia-Targeting Agent in Phase III Lung Cancer").
"We believe, therefore, that the assessment of tumor pO2 may represent a biological parameter we can use in the staging of our patients to go along with anatomic staging and allow us to select appropriate patients for either more or less intensive therapy," said Dr. Brizel, associate professor of radiation oncology at Duke.
The study evaluated tumor hypoxia in 49 of 56 patients with measurable nodal disease who underwent modified neck dissection. Tumor oxygenation was assessed before patients received radiotherapy, surgery, or chemotherapy by determining pO2 values at the primary site or in metastatic neck lymph nodes using polarographic tumor oxygenation.
During the polarographic process, an electrode connected to a computer-controlled servomotor makes several passes through the tumor and captures pO2 measurements at 100 to 200 discrete and individual points.
All patients in the study received 70 Gy of radiation therapy, at a rate of either 2 Gy per day or 1.25 Gy twice daily, directed to the primary site, with or without concurrent chemotherapy. Four to 8 weeks after radiotherapy, patients who had N2a disease underwent elective neck dissection whether or not they demonstrated a clinical response.