A short course of preoperative radiotherapy improves prognosis of operable rectal carcinoma: a case control study.

BACKGROUND/AIMS: Randomized Swedish studies demonstrate the efficacy of a 5-fraction course of preoperative radiotherapy for rectal carcinoma. The present study evaluates the results in a single Greek institution over a 10-year period, with a similar regimen. METHODOLOGY: During the period of 1995-2000, 150 consecutive patients with Dukes' B or C rectal cancer were matched to receive preoperative radiotherapy (Group I) or not (Group II). Seventy-five patients received pelvic radiotherapy of 2500cGY/5 fractions, followed by surgery within one week. Radiotherapy was delivered through 4 portals, with the patient lying in the prone position. A CT scan was used to define treatment volume. The 5-fraction course was used for lesions that seemed readily resectable. Patients in both groups received adjuvant chemotherapy. Local recurrence, disease-free interval and 5-year survival were evaluated and analyzed. RESULTS: The disease-free interval was significantly longer in Group I (p < 0.0005). This benefit was mainly due to a significantly lower incidence of local recurrence in Group I (9/75, 12%) compared with Group II (30/75, 40%) (p < 0.0005). The incidence of distant metastases was not significantly different between the 2 groups. The 5-year survival for all patients, who underwent "curative" surgery was significantly higher in Group I (77.3%) as compared to Group II (39%), (p < 0.0005). CONCLUSIONS: Patients with resectable rectal cancer who received 2500cGy/5 fractions preoperative radiotherapy to the pelvis had excellent local control of disease, longer disease-free interval and higher 5-year survival than patients who did not. These patients were able to undergo sphincter preserving surgery and adjuvant chemotherapy.

Dosimetry in translation total body irradiation technique: a computer treatment planning approach and an experimental study concerning lung sparing.

PURPOSE: To describe and evaluate a method that uses a 3-dimensional (3D) treatment planning system (TPS) to determine the relative dose to the lung, and to study the beam filtration required for lung sparing in translation total body irradiation (TBI). Special dosimetric problems related to moving couch were also considered. MATERIALS AND METHODS: The irradiation technique employed in our hospital is that of patient translation. The patient is positioned on a moving couch passing under a stationary Co-60 beam so that his/her entire body is irradiated. Measurements of basic data at source-skin distance (SSD)=150 cm were used to implement the Co-60 TBI unit to TPS (THERAPLAN plus), which was then used in dose computations. Two stationary, opposed anterior-posterior (40 x 40 cm) fields were employed to irradiate the Alderson phantom. The midline dose to either lung was computed and correction factors (CFs) were obtained that depend on the anatomy and densities of the tissues involved. These factors give the midline lung dose increase relative to the midline dose at the level of the mediastinum. Once the required lung dose was decided, the computed CF was used to estimate the filtration required from the measured broad beam attenuation data. The shielded lung dose distribution could be obtained from the TPS using a transmission corresponding to narrow beam geometry. To verify the TPS computations, measurements using a dosimeter and a diode system were carried out, employing solid water phantoms and the Alderson phantom. RESULTS: For the TPS employed, the computed midline CFs were lower than those measured in simple geometry phantoms for lung densities of 0.2-0.35 g/cm(3), by no more than 2%. For the Alderson phantom studied (lung density of 0.32 g/cm(3)), the computed CF was 1.11, which was 2% higher than the measured value. CONCLUSION: The advantages of a 3D TPS (dose distribution inside the lung, lung dose volume histograms [DVH], accurate attenuator shape from patient's anatomy etc.) allowed to study the lung dose in the Alderson phantom and to estimate the beam filtration required for lung sparing in TBI. The accuracy in lung dose computations, excluding the soft-tissue/lung interface was < or = 5%, which is within the clinical dose requirements. This procedure has been applied to a number of patients prior to their irradiation. Computations and in vivo measurements were in good agreement.