[en] Purpose: To determine how chemotherapy agents affect radiation dose parameters that correlate with acute hematologic toxicity (HT) in patients treated with pelvic intensity modulated radiation therapy (P-IMRT) and concurrent chemotherapy. Methods and Materials: We assessed HT in 141 patients who received P-IMRT for anal, gynecologic, rectal, or prostate cancers, 95 of whom received concurrent chemotherapy. Patients were separated into 4 groups: mitomycin (MMC) + 5-fluorouracil (5FU, 37 of 141), platinum ± 5FU (Cis, 32 of 141), 5FU (26 of 141), and P-IMRT alone (46 of 141). The pelvic bone was contoured as a surrogate for pelvic bone marrow (PBM) and divided into subsites: ilium, lower pelvis, and lumbosacral spine (LSS). The volumes of each region receiving 5-40 Gy were calculated. The endpoint for HT was grade ≥3 (HT3+) leukopenia, neutropenia or thrombocytopenia. Normal tissue complication probability was calculated using the Lyman-Kutcher-Burman model. Logistic regression was used to analyze association between HT3+ and dosimetric parameters. Results: Twenty-six patients experienced HT3+: 10 of 37 (27%) MMC, 14 of 32 (44%) Cis, 2 of 26 (8%) 5FU, and 0 of 46 P-IMRT. PBM dosimetric parameters were correlated with HT3+ in the MMC group but not in the Cis group. LSS dosimetric parameters were well correlated with HT3+ in both the MMC and Cis groups. Constrained optimization (0< n≤ 1) of the Lyman-Kutcher-Burman model resulted in n=1, m = 0.11, TD₅₀ = 31 Gy for LSS in the MMC group and n=1, m = 0.27, TD₅₀ = 35 Gy for LSS in the Cis group. Conclusions: The incidence of HT3+ depends on type of chemotherapy received. Patients receiving P-IMRT ± 5FU have better bone marrow tolerance than those receiving irradiation concurrent with either Cis or MMC. Treatment with MMC has a lower TD₅₀ and more steeply rising normal tissue complication probability curve compared with treatment with Cis. Dose tolerance of PBM and the LSS subsite may be lower for patients treated with MMC compared with Cis

[en] Gynecologic cancers are often asymmetric, yet current Ir-192 brachytherapy techniques provide only limited radial modulation of the dose. The shielded solutions investigated here solve this by providing the ability to modulate between highly asymmetric and radially symmetric dose distributions at a given location. To find applicator designs that can modulate between full dose and less than 50% dose, at the dimensions of the urethra, a 2D calculation algorithm was developed to narrow down the search space. Two shielding design types were then further investigated using Monte Carlo and Boltzmann-solver dose calculation algorithms. 3D printing techniques using ISO 10993 certified biocompatible plastics and 3D printable tungsten-loaded plastics were tested. It was also found that shadowing effects set by the shape of the shielding cannot be easily modulated out, hence careful design is required. The shielded applicator designs investigated here, allow for reduction of the dose by over 50% at 5 mm from the applicator surface in desired regions, while also allowing radially symmetric dose with isodose line deviations less than 0.5 mm from circular. The shielding designs were also chosen with treatment delivery time in mind. Treatment times for these shielded designs were found to be less than 1.4 times longer than a 6-channel unshielded cylinder for the equivalent fully symmetric dose distribution. The 2D calculation methods developed here provide a simple way to rapidly evaluate shielding designs, while the 3D printing techniques also allow for devices with novel shapes to be rapidly prototyped. Both TOPAS Monte Carlo and Acuros BV calculations show that significant dose shaping and organ at risk sparing can be achieved without significantly compromising the plan in regions that require the full dose. (paper)

[en] Purpose: To evaluate anal cancer uptake of F-18 fluorodeoxyglucose (FDG) measured as the maximum standardized uptake value (SUV_max) by positron emission tomography (PET) and its correlation with prognostic factors. Patients and methods: The study population consisted of 77 patients with stages 0-IIIB anal cancer who underwent pre-treatment FDG-PET. Tumor histology included 65 squamous cell, 11 basaloid, and 1 small cell cancers. SUV_max and sites of lymph node metastasis were recorded. We analyzed the association between SUV_max and prognostic factors. Results: The mean SUV_max was 10.0 (range 1.0-43.1). The stage distribution included: 2 stage 0, 7 stage I, 49 stage II, 10 stage IIIA, 9 stage IIIB. SUV_max and clinical tumor size were not associated (R² = 0.338). Histology did not significantly influence SUV_max (mean SUV_max 10.0 for squamous versus 9.90 for basaloid). Higher SUV_max was associated with an increased risk of nodal metastasis at diagnosis (p < 0.0001). Higher SUV_max was associated with worse disease-free survival (p = 0.05). Patients with high anal tumor SUV_max at diagnosis were at an increased risk of persistent or recurrent disease on post-therapy FDG-PET performed less than 4 months after completing therapy (p = 0.0402). Conclusions: SUV_max is a valuable biomarker of anal cancer prognosis, predicting increased risk of lymph node metastasis and worse disease-free survival.

[en] Purpose: Previous research showed that pretreatment uptake of F-18 fluorodeoxyglucose (FDG), as assessed by the maximal standardized uptake value (SUV_max) and the variability of uptake (FDG_hetero), predicted for posttreatment response in cervical cancer. In this pilot study, we evaluated the changes in SUV_max and FDG_hetero during concurrent chemoradiation for cervical cancer and their association with post-treatment response. Methods and Materials: Twenty-five patients with stage Ib1-IVa cervical cancer were enrolled. SUV_max, FDG_hetero, and metabolic tumor volume (MTV) were recorded from FDG-positron emission tomography (PET)/computed tomography (CT) scans performed pretreatment and during weeks 2 and 4 of treatment and were evaluated for changes and association with response assessed on 3-month post-treatment FDG-PET/CT. Results: For all patients, the average pretreatment SUV_max was 17.8, MTV was 55.4 cm³, and FDG_hetero was −1.33. A similar decline in SUV_max was seen at week 2 compared with baseline and week 4 compared with week 2 (34%). The areas of highest FDG uptake in the tumor remained relatively consistent on serial scans. Mean FDG_hetero decreased during treatment. For all patients, MTV decreased more from week 2 to week 4 than from pretreatment to week 2. By week 4, the average SUV_max had decreased by 57% and the MTV had decreased by 30%. Five patients showed persistent or new disease on 3-month post-treatment PET. These poor responders showed a higher average SUV_max, larger MTV, and greater heterogeneity at all 3 times. Week 4 SUV_max (P=.037), week 4 FDG_hetero (P=.005), pretreatment MTV (P=.008), and pretreatment FDG_hetero (P=.008) were all significantly associated with post-treatment PET response. Conclusions: SUV_max shows a consistent rate of decline during treatment and declines at a faster rate than MTV regresses. Based on this pilot study, pretreatment and week 4 of treatment represent the best time points for prediction of response.

[en] Purpose: Though radiation therapy is generally considered the most effective treatment for unresectable pilocytic astrocytomas in children, there are few data to support this claim. To examine the efficacy of radiation therapy for pediatric pilocytic astrocytomas, we retrospectively reviewed the experience at our institution. Methods and Materials: Thirty-five patients 18 years old or younger with unresectable tumors and without evidence of neurofibromatosis have been treated since 1982. Patients were treated with local radiation fields to a median dose of 54 Gy. Six patients were treated with radiosurgery to a median dose of 15.5 Gy. Five patients were treated with initial chemotherapy and irradiated after progression. Results: All patients were alive after a median follow-up of 5.0 years. However, progression-free survival was 68.7%. None of 11 infratentorial tumors progressed compared with 6 of 20 supratentorial tumors. A trend toward improved progression-free survival was seen with radiosurgery (80%) compared with external beam alone (66%), but this difference did not reach statistical significance. Eight of the 9 patients progressing after therapy did so within the irradiated volume. Conclusions: Although the survival of these children is excellent, almost one third of patients have progressive disease after definitive radiotherapy. Improvements in tumor control are needed in this patient population, and the optimal therapy has not been fully defined. Prospective trials comparing initial chemotherapy to radiation therapy are warranted.

[en] Purpose: To more accurately define clinical target volume for cervical cancer radiation treatment planning by evaluating tumor microscopic extension toward the uterus body (METU) in International Federation of Gynecology and Obstetrics stage Ib-IIa squamous cell carcinoma of the cervix (SCCC). Patients and Methods: In this multicenter study, surgical resection specimens from 318 cases of stage Ib-IIa SCCC that underwent radical hysterectomy were included. Patients who had undergone preoperative chemotherapy, radiation, or both were excluded from this study. Microscopic extension of primary tumor toward the uterus body was measured. The association between other pathologic factors and METU was analyzed. Results: Microscopic extension toward the uterus body was not common, with only 12.3% of patients (39 of 318) demonstrating METU. The mean (±SD) distance of METU was 0.32 ± 1.079 mm (range, 0-10 mm). Lymphovascular space invasion was associated with METU distance and occurrence rate. A margin of 5 mm added to gross tumor would adequately cover 99.4% and 99% of the METU in the whole group and in patients with lymphovascular space invasion, respectively. Conclusion: According to our analysis of 318 SCCC specimens for METU, using a 5-mm gross tumor volume to clinical target volume margin in the direction of the uterus should be adequate for International Federation of Gynecology and Obstetrics stage Ib-IIa SCCC. Considering the discrepancy between imaging and pathologic methods in determining gross tumor volume extent, we recommend a safer 10-mm margin in the uterine direction as the standard for clinical practice when using MRI for contouring tumor volume

[en] Purpose: This study aimed to evaluate the toxicity and clinical outcomes for cervical cancer patients treated definitively with intensity-modulated radiation therapy (IMRT) compared with non-IMRT treatment. Methods and Materials: This prospective cohort study included 452 patients with newly diagnosed cervical cancer treated with curative intent (135 IMRT and 317 non-IMRT). Treatment involved external irradiation and brachytherapy, and 85% of patients received concurrent chemotherapy. All IMRT patients underwent an F-18 fluorodeoxyglucose positron emission tomography (FDG-PET/CT) simulation. A 3-month post-therapy PET was obtained to evaluate treatment response. Toxicity was scored by the Common Terminology Criteria for Adverse Events Version 3.0. Results: The IMRT and non-IMRT groups had similar stage distribution and histology. For all patients, the post-therapy FDG-PET response correlated with overall recurrence risk (p < 0.0001) and cause-specific survival (p < 0.0001). Post-treatment FDG-PET findings were not significantly different between the IMRT and non-IMRT patients (p = 0.9774). The mean follow-up for all patients alive at the time of last follow-up was 52 months (72 months non-IMRT, 22 months IMRT). At last follow-up, 178 patients (39 IMRT, 139 non-IMRT) had developed a recurrence. The difference in recurrence-free survival between the two groups did not reach statistical significance (p = 0.0738), although the IMRT group showed better overall and cause-specific survivals (p < 0.0001). Of the patients, 62 patients (8 IMRT and 54 non-IMRT) developed Grade 3 or greater bowel or bladder complications, and by cumulative hazard function analysis the risk was significantly less for patients treated with IMRT (p = 0.0351). Conclusion: Cervical cancer patients treated with FDG-PET/CT-guided IMRT have improved survival and less treatment-related toxicity compared with patients treated with non-IMRT radiotherapy.