Small bowel and rectal toxicity after pelvic radiotherapy : histopathological development, the influence of ageing and modulation by conformal treatment

Throughout history, cancer has been one of the major causes of death. It has been estimated that in the western world approximately one in three people will develop some kind of cancer during their lifetime, and one in five will die of it. Longevity is associated with prolonged exposure of somatic cells to environmental carcinogens leading to carcinogenesis in these ageing cells. Therefore, cancer is predominantly a disease related to old age. In The Netherlands, the number of persons over 85 years of age increased from 99.000 in 1976 to 203.000 in 1995 (an increase of 1O5 %). It is predicted that by the year 2015 the total population living in The Netherlands will have increased by 8.4%, from 15.4 million in 1994 to 16.7 million. However the proportion of the population more than 65 years of age is expected to grow much faster (45%), although the proportion of persons of 85 years and older will remain the same. In view of the demographic developments, the number of cancer cases can be expected to increase dramatically in the near future. Compared to 1994, for 2015 an increase varying from 30-60 % for cancer of the colon, prostate and breast has been predicted

Evaluating AI-generated CBCT-based synthetic CT images for target delineation in palliative treatments of pelvic bone metastasis at conventional C-arm linacs

Purpose: One-table treatments with treatment imaging, preparation and delivery occurring at one treatment couch, could increase patients’ comfort and throughput for palliative treatments. On regular C-arm linacs, however, cone-beam CT (CBCT) imaging quality is currently insufficient. Therefore, our goal was to assess the suitability of AI-generated CBCT based synthetic CT (sCT) images for target delineation and treatment planning for palliative radiotherapy. Materials and methods: CBCTs and planning CT-scans of 22 female patients with pelvic bone metastasis were included. For each CBCT, a corresponding sCT image was generated by a deep learning model in ADMIRE 3.38.0. Radiation oncologists delineated 23 target volumes (TV) on the sCTs (TVsCT) and scored their delineation confidence. The delineations were transferred to planning CTs and manually adjusted if needed to yield gold standard target volumes (TVclin). TVsCT were geometrically compared to TVclin using Dice coefficient (DC) and Hausdorff Distance (HD). The dosimetric impact of TVsCT inaccuracies was evaluated for VMAT plans with different PTV margins. Results: Radiation oncologists scored the sCT quality as sufficient for 13/23 TVsCT (median: DC = 0.9, HD = 11 mm) and insufficient for 10/23 TVsCT (median: DC = 0.7, HD = 34 mm). For the sufficient category, remaining inaccuracies could be compensated by +1 to +4 mm additional margin to achieve coverage of V95% &gt; 95% and V95% &gt; 98%, respectively in 12/13 TVsCT. Conclusion: The evaluated sCT quality allowed for accurate delineation for most targets. sCTs with insufficient quality could be identified accurately upfront. A moderate PTV margin expansion could address remaining delineation inaccuracies. Therefore, these findings support further exploration of CBCT based one-table treatments on C-arm linacs.</p

Inguinal Lymph Node Recurrence in the Untreated Groin of Patients with Anal Carcinoma

BACKGROUND: Inguinal lymph node metastasis is predictive of locoregional recurrence and poor overall survival in anal carcinoma. Metachronous lymph node metastasis occurs in 10% of all anal cancer patients, but multiple studies have shown that the benefit of elective irradiation of the groin depends on T-stage, and the toxicity of groin irradiation must not be underestimated. OBJECTIVE: To analyze the inguinal recurrence rates among patients with anal carcinoma (T1-4, N0-1) who did not receive elective irradiation therapy to the groin and to determine predictors of inguinal recurrence. DESIGN: Data on 119 patients treated between 1987 and 2005 were retrospectively analyzed. Patients were treated with 3-dimensional radiotherapy. The median dose was 60 Gy. During radiotherapy, 108 patients also received chemotherapy (5-fluorouracil and mitomycin-C). RESULTS: AJCC staging showed a distribution of 21 T1 (18%), 58 T2 (49%), 27 T3 (23%), 13 T4 (11%), 101 N0 (85%) and 18 N1 (15%) tumors. The median follow up was 65 months (range, 1-240 months). The 5-year inguinal recurrence rate was 0% for T1, 10% for T2, 21% for T3 and 19% for T4 tumors (p = 0.034). T2 tumors of the perianal skin and the anal canal had 5-year inguinal recurrence rates of 12% and 8%, respectively. The 5-year inguinal recurrence rate was 21% for tumors = 4 cm vs. 2% for tumors <4 cm in size (p = 0.003). LIMITATIONS: Eleven patients did not receive chemotherapy. CONCLUSIONS: Elective irradiation of the groin should be considered for local control in patients (N0-N1) with T2 tumors = 4 cm in size and/or located in the perianal skin, and in all patients with T3 and T4 tumors