Mitsuhiro Sakai

Evaluation of the therapeutic effect of radiotherapy on cervical cancer using magnetic resonance imaging

PURPOSE This study was performed to evaluate magnetic resonance imaging (MRI) in determining the therapeutic effect of radiotherapy (RT) on cervical cancer. METHODS AND MATERIALS Serial MRI studies were performed in 42 patients with predominantly advanced cervical cancer before, during, and after radiotherapy. Patients underwent external irradiation combined with high-dose-rate intracavitary (HDR) brachytherapy. T-2 weighted spin-echo pulse sequences with long repetition and echo times were used at a field strength of 1.5 T. Multiple punch biopsies of the cervix were obtained from the high-signal intensity area in all patients at the same time as the MRI. RESULT In biopsies performed immediately after RT, no residual tumors were found in 36 patients (86%); in 6 patients, residual tumors were observed. The simultaneous MRI study demonstrated no high-signal intensity on T2-weighted images in 28 patients. A high-signal area was observed in 14 patients, and this disappeared 3 months after RT in 8 patients with a negative histological study. The sensitivity, specificity, and accuracy of MRI studies at 3 months after RT were 100%. When the relationship between reduction of tumor volume at 30 Gy and local tumor control was analyzed, every patient with a reduction under 30% gained local control. Also, patients with no residual tumors 3 months after RT gained local control. CONCLUSION MRI studies performed at 30 Gy of external irradiation and 3 months after RT were predictive factors of local control.

Phase II Study of Oral S-1 and Concurrent Radiotherapy in Patients With Unresectable Locally Advanced Pancreatic Cancer

PURPOSE S-1 is an oral fluoropyrimidine derivative that has demonstrated favorable antitumor activity in patients with metastatic pancreatic cancer. The aim of this study was to evaluate safety and efficacy of S-1 and concurrent radiotherapy in patients with unresectable locally advanced pancreatic cancer. METHODS AND MATERIALS Patients with histopathologically proven, unresectable, locally advanced pancreatic cancer were eligible. Radiotherapy was delivered in 1.8 Gy daily fractions to a total dose of 50.4 Gy over 5.5 weeks. S-1 was administered orally twice a day at a dose of 80 mg/m(2)/day from day 1 to 14 and 22 to 35. Two weeks after the completion of chemoradiotherapy, maintenance chemotherapy with S-1 was administered for 28 days every 6 weeks until progression. RESULTS Thirty-four patients were enrolled in this study. The most common Grade 3 toxicities during chemoradiotherapy were anorexia (24%) and nausea (12%). The overall response rate was 41% (95% confidence interval, 25%-58%) and overall disease control rate (partial response plus stable disease) was 97%. More than 50% decrease in serum CA 19-9 was seen in 27 of 29 evaluable patients (93%). The median progression-free survival was 8.7 months. The median overall survival and 1-year survival rate were 16.8 months and 70.6%, respectively. CONCLUSIONS Oral S-1 and concurrent radiotherapy exerted a promising antitumor activity with acceptable toxicity in patients with locally advanced pancreatic cancer. This combination therapy seems to be an attractive alternative to conventional chemoradiotherapy using 5-fluorouracil infusion.

Current status of intensity-modulated radiation therapy (IMRT)

External-beam radiation therapy has been one of the treatment options for prostate cancer. The dose response has been observed for a dose range of 64.8–81 Gy. The problem of external-beam RT for prostate cancer is that as the dose increases, adverse effects also increase. Three-dimensional conformal radiation therapy (3D-CRT) has enabled us to treat patients with up to 72–76 Gy to the prostate, with a relatively acceptable risk of late rectal bleeding. Recently, intensity-modulated radiation therapy (IMRT) has been shown to deliver a higher dose to the target with acceptable low rates of rectal and bladder complications. The most important things to keep in mind when using an IMRT technique are that there is a significant trade-off between coverage of the target, avoidance of adjacent critical structures, and the inhomogeneity of the dose within the target. Lastly, even with IMRT, it should be kept in mind that a “perfect” plan that creates completely homogeneous coverage of the target volume and zero or small dose to the adjacent organs at risk is not always obtained. Participating in many treatment planning sessions and arranging the beams and beam weights create the best approach to the best IMRT plan.