Postoperative irradiation for squamous cell carcinoma of the head and neck: an analysis of treatment results and complications.

One hundred thirty-four patients with advanced head and neck cancer were treated with radical surgery and postoperative radiation therapy between October 1964 and October 1984. All patients had greater than or equal to 2 years and 84% had greater than or equal to 5 years of follow-up. All patients included in the study were scheduled to receive continuous-course irradiation following a major cancer operation for previously untreated squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx and began radiation treatment less than or equal to 3 months after the surgical procedure. Ninety-six percent had AJCC pathologic Stage III or IV cancer, and all were without evidence of gross disease at the start of irradiation. The majority of recurrences above the clavicles occurred in the primary field (84%) as opposed to the posterior strip (8%) or low neck (8%). Based on multivariate analysis and tabular comparisons, 4 factors were found to be significantly important for predicting disease control above the clavicles: (a) Surgical margin (5-year actuarial control with invasive cancer at the margin, 53%, versus 81% with negative margins, p = .009). Patients with close margins or in situ cancer at the margins had the same rate of control as those with negative margins. (b) Primary site (oral cavity, 64%, versus other sites, 83%; p = .029). (c) Neck Stage (N0-1 versus N2-3). (d) Number of indications for irradiation--for example, bone invasion, multiple positive nodes, perineural invasion (1-3 indications, 85%, versus greater than or equal to 4, 62%; p = .06). The rate of disease control above the clavicles did not correlate well with AJCC pathologic stage: Stage I-II, 67%; Stage III, 81%; Stage IVA (T1-3, N2-3A), 68%; Stage IVB (T4 and/or N3B), 80%. The interval between surgery and the start of irradiation (range 1-10 weeks) also was not prognostically important, even with stratification by tumor dose, surgical margin, and number of indications for irradiation. At 5 years, the actuarial survival rate was 33% for the entire group; for patients with invasive cancer at the margin, the survival rate was approximately half that of those whose margins were free of invasive cancer (17% versus 37%). Based on multivariate analysis, 2 factors were found to significantly increase the probability of death due to cancer: (a) neck Stage (N0-1 versus N2-3); (b) extension of tumor from the primary site into the skin or soft tissues of the neck.(ABSTRACT TRUNCATED AT 400 WORDS)