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.