The lung is a major dose-limiting organ for radiation therapy (RT) for cancer in the thoracic region, and the clarification of radiation-induced lung damage (RILD) is important. However, there have been few reports containing a detailed comparison of radiographic images with the pathological findings of radiation pneumonitis (RP)/radiation fibrosis (RF). We recently reported the upregulated expression of tenascin-C (TNC), an inflammation-associated extracellular matrix molecule, in surgically resected lung tissue, and elevated serum levels were elevated in a RILD patient. Therefore, we have developed a novel mouse model of partial lung irradiation and studied it with special attention paid to the computed tomography (CT) images and immunohistological findings. The right lungs of mice (BALB/c) were irradiated locally at 30 Gy/1fr, and the following two groups were created. In Group 1, sequential CT was performed to confirm the time-dependent changes in RILD. In Group 2, the CT images and histopathological findings of the lung were compared. RP findings were detected histologically at 16 weeks after irradiation; they were also observed on the CT images from 20 weeks. The immunostaining of TNC was observed before the appearance of RP on the CT images. The findings suggest that TNC could be an inflammatory marker preceding lung fibrosis.

Radiation therapy, including external-beam radiation therapy (EBRT) and brachytherapy, is curative for localized prostate cancer. Hydrogel spacer (HS) placement between the rectum and prostate is popular for reducing radiation-related complications. Criteria to identify patients who benefit from HS placement would be clinically valuable. In a retrospective analysis of 430 patients with localized prostate cancer treated between November 2010 and March 2023 with ≥2 years of follow-up, we evaluated the incidence of rectal hemorrhage and its association with the median distance at the midpoint between the prostate and the rectum (mDPR) on pretreatment MRI. Rectal hemorrhage occurred in 6% of HS cases and 18% of non-HS cases (p < 0.001). Among 268 patients who received EBRT (±brachytherapy), the incidence was 9% with HS and 30% without HS (p < 0.001). In non-HS cases, the rate in patients with mDPR ≤ 1.62 mm was higher than in those with mDPR > 1.62 mm (24% vs. 12%, respectively; p = 0.04). In patients with EBRT and mDPR ≤ 1.62 mm, HS significantly reduced hemorrhage (9% vs. 39%, respectively; p < 0.001). Multivariate analysis identified mDPR and HS as independent predictors of rectal hemorrhage (both p = 0.02). Thus, HS placement may be safely omitted in non-EBRT cases with mDPR ≥ 1.62 mm.

Background: This study aimed to compare the outcomes and safety profiles of total neoadjuvant therapy (TNT) combined with dose-escalated intensity-modulated radiotherapy (IMRT) and conventional neoadjuvant chemoradiotherapy (NACRT) using three-dimensional conformal radiotherapy (3D-CRT) for locally advanced lower rectal cancer. Methods: This single-institution retrospective study included 51 patients treated with TNT using IMRT from 2018 to 2023 and 53 patients treated with conventional NACRT from 2001 to 2018. TNT consisted of IMRT at a total dose of 54 Gy with capecitabine, whereas NACRT consisted of 3D-CRT at a total dose of 45 Gy with a 5-fluorouracil-based regimen. Survival outcomes, treatment compliance, adverse events, surgical complications, and combined complete response (CR), defined as clinical CR plus pathological CR, were evaluated. Results: The combined CR rate was significantly higher in the TNT with IMRT group than in the NACRT group (43.1% vs. 5.7%). Overall survival and local recurrence-free survival did not differ significantly between the groups, whereas recurrence-free survival was significantly better in the TNT with IMRT group. Treatment compliance was comparable between the groups. Grade ≥ 3 adverse events during radiotherapy were less frequent in the TNT with IMRT group than in the NACRT group (7.8% vs. 22%), and major surgical complications did not differ significantly. Conclusions: TNT combined with dose-escalated IMRT was associated with a higher combined CR rate, favorable disease-free survival, and acceptable toxicity in this cohort. However, given the retrospective historical control design, chronological differences, follow-up imbalance, and potential residual confounding, these findings should be interpreted cautiously and require validation in prospective studies with longer follow-up.