Pre-operative hyperfractionated concurrent radiochemotherapy for locally advanced rectal cancers: a phase II clinical study

Radiation hematologic toxicity prediction for locally advanced rectal cancer using dosimetric and radiomics features

BACKGROUND

Hematologic toxicity (HT) is a common adverse tissue reaction during radiotherapy for rectal cancer patients, which may lead to various negative effects such as reduced therapeutic effect, prolonged treatment period and increased treatment cost. Therefore, predicting the occurrence of HT before radiotherapy is necessary but still challenging.

PURPOSE

This study proposes a hybrid machine learning model to predict the symptomatic radiation HT in rectal cancer patients using the combined demographic, clinical, dosimetric, and Radiomics features, and ascertains the most effective regions of interest (ROI) in CT images and predictive feature sets.

METHODS

A discovery dataset of 240 rectal cancer patients, including 145 patients with HT symptoms and a validation dataset of 96 patients (63 patients with HT) with different dose prescription were retrospectively enrolled. Eight ROIs were contoured on patient CT images to derive Radiomics features, which were then, respectively, combined with the demographic, clinical, and dosimetric features to classify patients with HT symptoms. Moreover, the survival analysis was performed on risky patients with HT in order to understand the HT progression.

RESULTS

The classification models in ROIs of bone marrow and femoral head exhibited relatively high accuracies (accuracy = 0.765 and 0.725) in the discovery dataset as well as comparable performances in the validation dataset (accuracy = 0.758 and 0.714). When combining the two ROIs together, the model performance was the best in both discovery and validation datasets (accuracy = 0.843 and 0.802). In the survival analysis test, only the bone marrow ROI achieved statistically significant performance in accessing risky HT (C-index = 0.658, P = 0.03). Most of the discriminative features were Radiomics features, and only gender and the mean dose in Irradvolume was involved in HT.

CONCLUSION

The results reflect that the Radiomics features of bone marrow are significantly correlated with HT occurrence and progression in rectal cancer. The proposed Radiomics-based model may help the early detection of radiotherapy induced HT in rectal cancer patients and thus improve the clinical outcome in future.

Hyperfractionation versus Conventional Fractionation of Preoperative Intensity-Modulated Radiotherapy with Oral Capecitabine in Locally Advanced Mid-Low Rectal Cancer: A Propensity Score Matching Study

Purpose

In theory, the hyperfractionated radiotherapy can enhance biological effect dose against tumor and alleviate normal tissue toxicity. This study is to assess the efficacy and safety of preoperative hyperfractionated intensity-modulated radiotherapy (IMRT) with oral capecitabine in patients with locally advanced rectal cancer (LARC).

Methods

We retrospectively screened patients with LARC from January 2015 to June 2016. Patients that received hyperfractionated IMRT or conventional fractionated IMRT were eligible in the hyperfractionation (HF) group or conventional fractionation (CF) group, respectively. The primary outcome was the complete response rate. Secondary outcomes included toxicity, postoperative complications, anus-reservation operation rate, local recurrence and distant metastases rate, overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS).

Results

335 patients were included in the analysis. The complete response rate for the hyperfractionated and conventional fractionated IMRT was 20.41% vs. 23.47% (P = 0.583). The anus-reservation operation rate was 68.37% vs. 65.31% (P = 0.649). There were no cases of grade 4 toxicity during radiotherapy; the rate of grade 3 toxicity and postoperative complications was both comparable between groups. However, in the CF group, more patients had a second operation due to complications (0.0% vs. 5.68%, P = 0.011). The cumulative local regional recurrence and distant metastases rates of the HF group and CF group were 5.10% vs. 9.18% (P = 0.267) and 22.45% vs. 24.49% (P = 0.736), respectively. The 5-year OS, CSS, and DFS in the HF group and CF group were 86.45% vs. 73.30% (P = 0.503), 87.34% vs. 75.23% (P = 0.634), and 70.80% vs. 68.11% (P = 0.891), respectively.

Conclusions

The preoperative hyperfractionated IMRT with oral capecitabine, with an acceptable toxicity and favorable response and survival, could reduce the rate of secondary surgery.

Recent advances in (chemo-)radiation therapy for rectal cancer: a comprehensive review

The role of radiation therapy in the treatment of (colo)-rectal cancer has changed dramatically over the past decades. Introduced with the aim of reducing the high rates of local recurrences after conventional surgery, major developments in imaging, surgical technique, systemic therapy and radiation delivery have now created a much more complex environment leading to a more personalized approach. Functional aspects including reduction of acute or late treatment-related side effects, sphincter or even organ-preservation and the unsolved problem of still high distant failure rates have become more important while local recurrence rates can be kept low in the vast majority of patients. This review summarizes the actual role of radiation therapy in different subgroups of patients with rectal cancer, including the current standard approach in different subgroups as well as recent developments focusing on neoadjuvant treatment intensification and/or non-operative treatment approaches aiming at organ-preservation.

Dose-time fractionation schedules of preoperative radiotherapy and timing to surgery for rectal cancer

Chemoradiotherapy (CRT) is extensively used prior to surgery for rectal cancer to provide significantly better local control, but the radiotherapy (RT), as the other component of CRT, has been subject to less interest than the drug component in recent years. With considerable developments in RT, the use of advanced techniques, such as intensity-modulated radiotherapy (IMRT) in rectal cancer, is garnering more attention nowadays. The radiation dose can be better conformed to the target volumes with possibilities for synchronous integrated boost without increased complications in normal tissue. Hopefully, both local recurrence and toxicities can be further reduced. Although those seem to be of interest, many issues remain unresolved. There is no international consensus regarding the radiation schedule for preoperative RT for rectal cancer. Moreover, an enormous disparity exists regarding the RT delivery. With the advent of IMRT, variations will likely increase. Moreover, time to surgery is also quite variable, as it depends upon the indication for RT/CRT in the clinical practices. In this review, we discuss the options and problems related to both the dose-time fractionation schedule and time to surgery; furthermore, it addresses the research questions that need answering in the future.