Tumor size, irradiation dose, and long-term outcome of carcinoma of uterine cervix

Abstract

Purpose: To assess the impact of tumor size and extent, and dose of irradiation on pelvic tumor control, incidence of distant metastases, and disease-free survival in carcinoma of the uterine cervix.

Methods and materials: Records were reviewed of 1499 patients (Stages IA-IVA) treated with definitive irradiation (combination of external beam plus two intracavitary insertions to deliver doses of 65-95 Gy to point A, depending on stage and tumor volume). Follow-up was obtained in 98% of patients (median 11 years, minimum 3 years, maximum 30 years). The relationship between outcome and tumor size was analyzed in each stage. Pelvic tumor control was correlated with total doses to point A and to the lateral pelvic wall.

Results: The 10-year actuarial pelvic failure rate in Stage IB was 5% for tumors <2 cm, 15% for 2.1-5 cm, and 35% for tumors >5 cm (p = 0.01); in Stage IIA, the rates were 0%, 28%, and 25%, respectively (p = 0.12). Stage IIB unilateral or bilateral nonbulky tumors <5 cm had a 23% pelvic failure rate compared with 34% for unilateral or bilateral bulky tumors >5 cm (p = 0.13). In Stage IIB, pelvic failures were 18% with medial parametrial involvement only, compared with 28% when tumor extended into the lateral parametrium (p = 0.05). In Stage III, unilateral parametrial involvement was associated with a 32% pelvic failure rate versus 50% for bilateral extension (p < 0.01). Ten-year disease-free survival rates were 90% for IB tumors <2 cm, 76% for 2.1-4 cm, 61% for 4.1-5 cm, and 47% for >5 cm (p = 0.01); in Stage IIA, the rates were 93%, 63%, 39%, and 59%, respectively (p < or = 0.01). Patients with Stage IIB medial parametrial involvement had better 10-year disease-free survival (67%) than those with lateral parametrial extension (56%) (p = 0.02). Stage III patients with unilateral tumor extension had a 48% 10-year disease-free survival rate compared with 32% for bilateral parametrial involvement (p < or = 0.01). The presence of endometrial extension or tumor only in the endometrial curettings had no significant impact on pelvic failure. However, in patients with Stage IB disease, the incidence of distant metastases was 31% with positive curettings, 15% with negative curettings, and 22% with admixture (p < or = 0.01). In Stage IIA, the corresponding values were 51%, 33%, and 18% (p = 0.05). The 10-year disease-free survival rates in Stage IB were 67% with positive curettings, 81% for negative curettings, and 77% for admixture (p = 0.02); in Stage IIA, the rates were 45%, 66%, and 67%, respectively (p = 0.14). Because this is not a prospective Phase II dose-escalation study, the correlation of doses of irradiation with pelvic tumor control in the various stages and tumor size groups is not consistent. Nevertheless, with Stage IB and IIA tumors <2 cm in diameter, the pelvic failure rate was under 10% with doses of 70-80 Gy to point A, whereas for larger lesions even doses of 85-90 Gy resulted in 25% to 37% pelvic failure rates. In Stage IIB with doses of 70 Gy to point A, the pelvic failure rate was about 50% compared with about 20% in nonbulky and 30% in bulky tumors with doses > 80 Gy. In Stage III unilateral lesions, the pelvic failure rate was about 50% with < or =70 Gy to point A versus 35% with higher doses, and in bilateral or bulky tumors it was 60% with doses <70 Gy and 50% with higher doses.

Conclusions: Clinical stage and size of tumor are critical factors in prognosis, therapy efficacy, and evaluation of results in carcinoma of the uterine cervix. The doses to point A suggest that for lesions <2 cm, doses of 75 Gy result in < or =10% pelvic failures, whereas in more extensive lesions, even with doses of 85 Gy, the pelvic failure rate is about 30%; and in Stage IIB-III tumors, doses of 85 Gy result in 35-50% pelvic failures. Refinements in brachytherapy techniques and/or use of agents to selectively sensitize the tumors to irradiation will be necessary to improve the present results in invasive carcinoma of t