The effect of overall treatment time on the outcome of definitive radiotherapy for localized prostate carcinoma: the Radiation Therapy Oncology Group 75-06 and 77-06 experience

Prostate cancer. Radiation therapy for localized disease

BACKGROUND

Since 1910, a variety of radiation modalities, including radioactive isotopes, photons, and particle beams, have been used to treat prostatic cancer.

METHODS

This report focuses on external beam x-irradiation produced by medium energy linear accelerators. Between 1956 and 1990, 1119 patients have been treated with curative intent at Stanford University. Tumor doses of 70 Gy delivered at 10 Gy/wk have been safe and effective.

RESULTS

Fifteen-year survival rates ranging from 50%, equivalent to that of an age-matched cohort, for the least extensively localized tumors to 18% for the most extensive have been achieved. Survival is inversely proportional to clinical stage and histopathologic grade.

CONCLUSION

Although external beam radiation therapy has been found to be safe and effective for the treatment of prostatic cancer, improvement in results of treatment of the more advanced tumors might be achieved by combining external beam and interstitial irradiation. This would achieve a higher radiation dose within the tumor. Alternatively, the treatment can be augmented with hyperthermia or other sensitizers in order to achieve a higher biological dose.

Effect of tumor size on the prognosis of carcinoma of the uterine cervix treated with irradiation alone

The authors conducted a retrospective analysis of 1178 patients with histologically proven invasive carcinoma of the uterine cervix treated with irradiation alone. The minimum follow-up time was 3 years. The 10-year actuarial pelvic failure rate in Stage IB was 6% for tumors less than 3 cm, 15% for tumors 3 to 5 cm, and 30% for tumors more than 5 cm (P = 0.0018). The 10-year actuarial pelvic failure rate in Stage IIA was 10% for tumors less than 3 cm, 28% for tumors 3 to 5 cm, and 20% for tumors more than 5 cm (P = 0.09). Stage IIB unilateral nonbulky tumors (less than 5 cm) had a 20% pelvic failure rate compared with 28% for bilateral lesions and 35% for unilateral bulky tumors (more than 5 cm) (P = 0.35). In Stage IIB, pelvic failures were greater when disease extended into the lateral parametrium (30%) compared with medial parametrial involvement only (17%) (P = 0.01). In Stage III unilateral nonbulky tumors, the pelvic failure rate was 28% compared with 45% to 50% for unilateral bulky lesions (P = 0.002). Bilateral parametrial disease in Stage IIB did not increase the pelvic failure rate (21% in both subgroups) (P = 0.83), whereas in Stage III, bilateral parametrial involvement was associated with a 48% pelvic failure rate versus 28% for unilateral extension (P less than or equal to 0.01). Five-year disease-free survival (DFS) rates for IB tumors less than or equal to 3 cm was 90% versus 67% for tumors more than 3 cm (P = 0.01). In Stage IIA tumors less than or equal to 3 cm, 5-year DFS was 70% versus 45% for tumors more than 3 cm. Patients with Stage IIB nonbulky tumors (less than or equal to 5 cm in diameter) had better 10-year DFS (65% to 70%) compared with those with bilateral bulky tumors (45% to 55%) (P = 0.10). Stage III patients with unilateral nonbulky tumors had a 55% 10-year DFS compared with 35% to 40% for bulky tumors or bilateral parametrial involvement (P = 0.002). The authors concluded that clinical stage and size of tumor are critical factors in the prognosis, therapy selection, and evaluation of results in carcinoma of the uterine cervix.

Conformal static field radiation therapy treatment of early prostate cancer versus non-conformal techniques: a reduction in acute morbidity

Patients with early prostate cancer have been definitively treated using our previously described technique of CT-based 3D treatment planning and beam's eye view techniques with patients immobilized in alpha cradle casts. An average of 14% bladder (range 6-31%) and 14% rectal (range 7-25%) volume receiving a given dose was eliminated using four conformally blocked fields, with a 1.5 cm margin around the prostate contour, when compared to stage matched controls. Treatment-related acute morbidity was compared for 26 patients treated by the conformal techniques (CG) since April 1989 and 20 consecutive patients treated immediately prior to the conformal techniques with prostate only fields from May 1985-March 1989 (NCG). Acute urinary symptoms (frequency, dysuria, hematuria) or acute rectal symptoms (diarrhea, tenesmus, blood) occurred in 77% (20/26) of the CG versus 80% (16/20) of the NCG patients. Only 31% (8/26) of the CG versus 60% (12/20) of the NCG patients (p < .05) experienced symptoms to a degree which prompted physician intervention (medication and/or interruption of treatment). Two of 26 CG patients (8%) required medication for both bladder and rectal symptoms compared to 5/20 (25%) NCG patients (p = .09). Symptoms persisted for an average of 2.5 weeks versus 3.5 weeks in the CG and NCG groups, respectively. Persistent symptoms at or beyond the 1 month follow-up were present in 3/26 (11%) CG patients (average duration 1.5 months) and were present in 4/20 (20%) of the NCG patients (average duration 2.5 months). Thus, although the percentage of patients who experience acute irritation of the bladder and/or rectum is similar in the two groups, it appears that the percentage requiring medication and/or interruption of treatment is significantly less when 3D treatment planning, rigid immobilization, and conformal blocks are used. The amount of bladder and rectal tissue that is eliminated by our conformal technique is important as shown clinically by the lesser severity and shorter duration of acute symptomatology.