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Biomedical subjects

Christopher Willett

Publications and source records attributed to Christopher Willett.

9 recordsLinked to original sources
PubMed2006

Phase II trial of preoperative chemoradiation in patients with localized gastric adenocarcinoma (RTOG 9904): quality of combined modality therapy and pathologic response.

PURPOSE: Preoperative therapy for localized gastric cancer has considerable appeal. We hypothesized that, in a cooperative group setting, preoperative chemoradiotherapy would induce a 20% pathologic complete response (pathCR) rate. Combined-modality therapy quality, survival, and safety were secondary end points. PATIENTS AND METHODS: Patients with localized gastric adenocarcinoma were eligible. A negative laparoscopic evaluation was required. Patients received two cycles of induction fluorouracil, leucovorin, and cisplatin followed by concurrent radiation and chemotherapy (infusional fluorouracil and weekly paclitaxel). Resection was attempted 5 to 6 weeks after chemoradiotherapy was completed. Quality of therapy was assessed with other end points. RESULTS: Twenty institutions participated. Forty-nine patients were entered and 43 were assessable (12% stage IB; 37% stage II; and 52% stage III). The pathCR and R0 resection rates were 26% and 77%, respectively. At 1 year, more patients with pathCR (82%) are living than those with less than pathCR (69%). Grade 4 toxicity occurred in 21% of patients. Chemotherapy, radiotherapy, and surgery per protocol (including acceptable variations) occurred in 98%, 44%, and 63% of patients, respectively. A D2 dissection was performed in 50% of patients. Of 18 major radiotherapy variations, 17 were due to the lack of inclusion of the L3-4 vertebral interphase as prespecified. CONCLUSION: For localized gastric cancer, preoperative chemoradiotherapy strategy achieved a pathCR rate of more than 20% in a cooperative group setting. The quality of surgery improved (50% with D2 dissection) possibly because surgery was part of this trial. With some refinements, this preoperative chemoradiotherapy strategy is poised for a randomized comparison with postoperative adjuvant chemoradiotherapy in patients with gastric cancer.

Adenocarcinoma↗
PubMed2006

Digital tomosynthesis with an on-board kilovoltage imaging device.

PURPOSE: To generate on-board digital tomosynthesis (DTS) and reference DTS images for three-dimensional image-guided radiation therapy (IGRT) as an alternative to conventional portal imaging or on-board cone-beam computed tomography (CBCT). METHODS AND MATERIALS: Three clinical cases (prostate, head-and-neck, and liver) were selected to illustrate the capabilities of on-board DTS for IGRT. Corresponding reference DTS images were reconstructed from digitally reconstructed radiographs computed from planning CT image sets. The effect of scan angle on DTS slice thickness was examined by computing the mutual information between coincident CBCT and DTS images, as the DTS scan angle was varied from 0 degrees to 165 degrees . A breath-hold DTS acquisition strategy was implemented to remove respiratory motion artifacts. RESULTS: Digital tomosynthesis slices appeared similar to coincident CBCT planes and yielded substantially more anatomic information than either kilovoltage or megavoltage radiographs. Breath-hold DTS acquisition improved soft-tissue visibility by suppressing respiratory motion. CONCLUSIONS: Improved bony and soft-tissue visibility in DTS images is likely to improve target localization compared with radiographic verification techniques and might allow for daily localization of a soft-tissue target. Breath-hold DTS is a potential alternative to on-board CBCT for sites prone to respiratory motion.

Algorithms↗
PubMed2006

Randomized phase II study of neoadjuvant combined-modality chemoradiation for distal rectal cancer: Radiation Therapy Oncology Group Trial 0012.

PURPOSE: To evaluate the rate of pathologic complete response and toxicity of neoadjuvant chemoradiation for advanced T3/T4 distal rectal cancers in a randomized phase II study PATIENTS AND METHODS: Patients with clinical T3/T4 distal rectal cancers were randomly assigned in a phase II study to receive combined neoadjuvant chemoradiotherapy followed by surgical resection. Patients were randomly assigned to receive continuous venous infusion (CVI) fluorouracil (FU) 225 mg/m2 per day, 7 days per week, plus pelvic hyperfractionated radiation 55.2 to 60 Gy at 1.2 Gy bid (arm 1) or CVI FU 225 mg/m2 per day Monday to Friday, 120 hours per week plus irinotecan 50 mg/m2 once weekly for 4 weeks plus pelvic radiation therapy 50.4 to 54 Gy at 1.8 Gy per day (arm 2). Surgery was performed 4 to 10 weeks after completion of neoadjuvant therapy. The primary end point of this study was pathologic complete response (pCR). Secondary end points included acute and late normal tissue morbidity. RESULTS: A total of 106 patients were entered onto the study, with 103 assessable for response. The overall resectability rate was 93%. The median time to surgery was 7 weeks. Tumor downstaging was observed in 78% of patients in both arms. The pCR rate for all assessable patients was 26% in each arm. For patients who had surgery, the pCR rate was also the same (28%) in both arms. Acute and late toxicity was also similar. Grade 3 and 4 acute hematologic and nonhematologic toxicity occurred in 13% and 38% in arm 1 and 12% and 45% in arm 2, respectively. CONCLUSION: Although the overall complete response rate and toxicity seems similar in both arms, this is the first multi-institutional study to establish a relatively high (28%) pCR rate after neoadjuvant therapy.

Adult↗
PubMed2006

Detection of stool DNA mutations before and after treatment of colorectal neoplasia.

BACKGROUND: Whether stool DNA abnormalities arise solely from colorectal neoplastic lesions or are due to more pervasive field effects is not known. In the current study, the authors conducted a prospective multicenter study to evaluate the performance of stool-based DNA testing in a large cohort and to examine whether the findings before treatment persist after surgical resection and/or adjuvant therapy. METHODS: Patients with newly diagnosed colorectal carcinoma or advanced adenomas (AA) provided stool samples before therapy, 1-3 months after surgical resection, and 6-9 months postresection. Stool samples were analyzed using the multi-target DNA assay panel (MTAP) consisting of 23 markers: 21 mutations in the p53, K-ras, and APC genes, a microsatellite instability marker (BAT-26), and the DNA integrity assay (DIA), a marker of loss of apoptosis. RESULTS: Overall, 49 of 91 individuals (54%) tested positive with the MTAP test. The sensitivity of the MTAP test was 63% for invasive tumors compared with 26% for AA. Individuals whose lesions had a more advanced TNM stage or were located distal to the splenic flexure were significantly more likely to have a positive MTAP test. Of the 79 samples collected at 1-3 months after surgical resection of the neoplasm, 14 (18%) had a positive MTAP result, 12 of which were positive for DIA only. Of those collected at 6-9 months of follow-up, 5 of 72 (7%) tested positive on the MTAP panel. CONCLUSIONS: Although many samples collected 1-3 months after surgical resection of the colorectal neoplasm tested positive on the MTAP, most were negative by 6-9 months, indicating that stool DNA abnormalities disappear after treatment of the neoplastic lesions. Surgery and chemoradiation appear to induce transient DIA abnormalities that may be independent of the presence of neoplasia.

Adult↗
PubMed2004

Impact of body mass index on outcomes and treatment-related toxicity in patients with stage II and III rectal cancer: findings from Intergroup Trial 0114.

PURPOSE: To study the relationship between body mass index (BMI) and rates of sphincter-preserving operations, overall survival, cancer recurrence, and treatment-related toxicities in patients with rectal cancer. PATIENTS AND METHODS: We evaluated a nested cohort of 1,688 patients with stage II and III rectal cancer participating in a randomized trial of postoperative fluorouracil-based chemotherapy and radiation therapy. RESULTS: Obese patients were more likely to undergo an abdominoperineal resection (APR) than normal-weight patients (odds ratio, 1.77; 95% CI, 1.27 to 2.46). When analyzed by sex, increasing adiposity in men was a strong predictor of having an APR (P <.0001). Obese men with rectal cancer were also more likely than normal-weight men to have a local recurrence (hazard ratio [HR], 1.61; 95% CI, 1.00 to 2.59). In contrast, obesity was not predictive of cancer recurrence in women, nor was BMI predictive of overall mortality in either men or women. Underweight patients had an increased risk of death (HR, 1.43; 95% CI, 1.08 to 1.89) compared with normal-weight patients but no increase in cancer recurrences. Among all study participants, obese patients had a significantly lower rate of grade 3 to 4 leukopenia, neutropenia, and stomatitis and a lower rate of any grade 3 or worse toxicity when compared with normal-weight individuals. CONCLUSION: Increasing BMI in male patients with rectal cancer is associated with a decreased likelihood of sphincter preservation and a higher chance of local recurrence. For both men and women, overweight and obese patients experience less toxicity associated with adjuvant chemoradiotherapy, suggesting that actual body weight dosing of fluorouracil for obese patients is justified.

Antineoplastic Agents↗
PubMed2002

Gastric surgical adjuvant radiotherapy consensus report: rationale and treatment implementation.

PURPOSE: Radiation therapy has recently emerged as a pivotal modality in the management of completely resected, high-risk gastric cancer. The recently published results of the Intergroup 0116 Gastric Surgical Adjuvant Trial randomized high-risk (T3,4 and/or node positive), completely resected gastric or gastroesophageal adenocarcinomas to receive either observation alone or radiochemotherapy after complete resection. Radiochemotherapy produced significant improvements in relapse-free (p < 0.0001) and overall survival (p = 0.01). Radiation oncologists must now clearly comprehend the principles governing the rationale supporting this therapy to apply it to those afflicted with this disease. This paper represents a consensus report reviewing data supporting radiotherapy, important clinical and anatomic issues related to radiotherapy, and details of the practical application of radiation therapy to commonly occurring clinical presentations. Supportive therapy during and after radiochemotherapy is also discussed.

Chemotherapy, Adjuvant↗