Superior outcomes of nodal metastases compared to visceral sites in oligometastatic colorectal cancer treated with stereotactic ablative radiotherapy

Stereotactic body radiation therapy for colorectal cancer liver metastases

The management of colorectal cancer liver metastases requires a multidisciplinary approach, which may incorporate systemic therapy, surgery, or local ablative therapies. Stereotactic body radiation therapy (SBRT) is a non-invasive highly conformal radiation technique that enables the delivery of large doses of radiation in a few fractions to well-defined targets using image-guidance and motion management. For selected patients with colorectal cancer liver metastases, stereotactic body radiation therapy can be delivered safely, with excellent long-term local control and overall survival. The purpose of this clinical practice review is to review the background, indications, and treatment details of stereotactic body radiation therapy for the treatment of colorectal liver metastases. SBRT for colorectal cancer liver metastases may be considered for patients with oligometastatic colorectal cancer in combination with surgery or other locally ablative therapies; for patients who are not candidates for surgical resection; or after failure of resection or other ablative therapies. When planning SBRT both a computed tomography and magnetic resonance imaging simulation may be obtained, where feasible, for target delineation. One or 3 fraction SBRT can be considered for lesions away from the central liver and luminal organs at risk, whereas 5 fraction SBRT is preferred otherwise. Image-guidance and motion management strategies are essential components of liver SBRT and will guide the creation of relevant internal and planning target volume margins. For lesions in close proximity to or overlapping with organs-at-risk, the balance between adequate local control and potential for cure with potential acute and late toxicity must be carefully considered.

Differential Perspectives by Specialty on Oligometastatic Colorectal Cancer: A Korean Oligometastasis Working Group's Comparative Survey Study

PURPOSE

Despite numerous studies on the optimal treatments for oligometastatic disease (OMD), there is no established interdisciplinary consensus on its diagnosis or classification. This survey-based study aimed to analyze the differential opinions of colorectal surgeons and radiation oncologists regarding the definition and treatment of OMD from the colorectal primary.

MATERIALS AND METHODS

A total of 141 participants were included in this study, consisting of 63 radiation oncologists (44.7%) and 78 colorectal surgeons (55.3%). The survey consisted of 19 questions related to OMD, and the responses were analyzed using the chi-square test to determine statistical differences between the specialties.

RESULTS

The radiation oncologists chose "bone" more frequently compared to the colorectal surgeons (19.2% vs. 36.5%, p=0.022), while colorectal surgeons favored "peritoneal seeding" (26.9% vs. 9.5%, p=0.009). Regarding the number of metastatic tumors, 48.3% of colorectal surgeons responded that "irrelevant, if all metastatic lesions are amendable to local therapy", while only 21.8% of radiation oncologist chose same answer. When asked about molecular diagnosis, most surgeons (74.8%) said it was important, but only 35.8% of radiation oncologists agreed.

CONCLUSION

This study demonstrates that although radiation oncologists and colorectal surgeons agreed on a majority of aspects such as diagnostic imaging, biomarker, systemic therapy, and optimal timing of OMD, they also had quite different perspectives on several aspects of OMD. Understanding these differences is crucial to achieving multidisciplinary consensus on the definition and optimal management of OMD.

Development and validation of a competitive risk model in patients with rectal cancer: based on SEER database

BACKGROUND

Rectal cancer is one of the most common malignancies. To predict the specific mortality risk of rectal cancer patients, we constructed a predictive nomogram based on a competing risk model.

METHODS

The information on rectal cancer patients was extracted from the SEER database. Traditional survival analysis and specific death analysis were performed separately on the data.

RESULTS

The present study included 23,680 patients, with 16,580 in the training set and 7100 in the validation set. The specific mortality rate calculated by the competing risk model was lower than that of the traditional survival analysis. Age, Marriage, Race, Sex, ICD-O-3Hist/Behav, Grade, AJCC stage, T stage, N stage, Surgery, Examined LN, RX SUMM-SURG OTH, Chemotherapy, CEA, Deposits, Regional nodes positive, Brain, Bone, Liver, Lung, Tumor size, and Malignant were independent influencing factors of specific death. The overall C statistic of the model in the training set was 0.821 (Se = 0.001), and the areas under the ROC curve for cancer-specific survival (CSS) at 1, 3, and 5 years were 0.842, 0.830, and 0.812, respectively. The overall C statistic of the model in the validation set was 0.829 (Se = 0.002), and the areas under the ROC curve for CSS at 1, 3, and 5 years were 0.851, 0.836, and 0.813, respectively.

CONCLUSIONS

The predictive nomogram based on a competing risk model for time-specific mortality in patients with rectal cancer has very desirable accuracy. Thus, the application of the predictive nomogram in clinical practice can help physicians make clinical decisions and follow-up strategies.

Magnetic resonance-guided stereotactic body radiation therapy (MRgSBRT) for oligometastatic patients: a single-center experience

PURPOSE

Stereotactic body radiotherapy is increasingly used for the treatment of oligometastatic disease. Magnetic resonance-guided stereotactic radiotherapy (MRgSBRT) offers the opportunity to perform dose escalation protocols while reducing the unnecessary irradiation of the surrounding organs at risk. The aim of this retrospective, monoinstitutional study is to evaluate the feasibility and clinical benefit (CB) of MRgSBRT in the setting of oligometastatic patients.

MATERIALS AND METHODS

Data from oligometastatic patients treated with MRgSBRT were collected. The primary objectives were to define the 12-month progression-free survival (PFS) and local progression-free survival (LPFS) and 24-month overall survival (OS) rate. The objective response rate (ORR) included complete response (CR) and partial response (PR). CB was defined as the achievement of ORR and stable disease (SD). Toxicities were also assessed according to the CTCAE version 5.0 scale.

RESULTS

From February 2017 to March 2021, 59 consecutive patients with a total of 80 lesions were treated by MRgSBRT on a 0.35 T hybrid unit. CR and PR as well as SD were observed in 30 (37.5%), 7 (8.75%), and 17 (21.25%) lesions, respectively. Furthermore, CB was evaluated at a rate of 67.5% with an ORR of 46.25%. Median follow-up time was 14 months (range: 3-46 months). The 12-month LPFS and PFS rates were 70% and 23%, while 24-month OS rate was 93%. No acute toxicity was reported, whereas late pulmonary fibrosis G1 was observed in 9 patients (15.25%).

CONCLUSION

MRgSBRT was well tolerated by patients with reported low toxicity levels and a satisfying CB.

Unravelling oligometastatic disease from the perspective of radiation and medical oncology. Part II: prostate cancer and colorectal cancer

Oligometastatic disease (OMD) defines a status of cancer that is intermediate between localized and widely spread metastatic disease, and can be treated with curative intent. While imaging diagnostic tools have considerably improved in recent years, unidentified micrometastases can still escape from current detection techniques allowing disease to progress. The variety of OMD scenarios are mainly defined by the number of metastases, the biological and molecular tumour profiles, and the timing of the development of metastases. Increasing knowledge has contributed to the earlier and improved detection of OMD, underlining the importance of an early disease control. Based on increasing detection rates of OMD in the current real clinical practice and the lack of standardized evidence-based guidelines to treat this cancer status, a board of experts from the Spanish Societies of Radiation Oncology (SEOR) and Medical Oncology (SEOM) organized a series of sessions to update the current state-of-the-art on OMD from a multidisciplinary perspective, and to discuss how results from clinical studies may translate into promising treatment options. This experts' review series summarizes what is known and what it is pending clarification in the context of OMD in the scenarios of Non-Small Cell Lung Cancer and Breast Cancer (Part I), and Prostate Cancer and Colorectal Cancer (Part II), aiming to offer specialists a pragmatic framework that might contribute to the improved management of patients.

The evolving role of radiation therapy as treatment for liver metastases

Liver metastases occur commonly in many solid malignancies. With advances in systemic therapies and increased life expectancy, the role of using local therapies in oligo-metastases is rapidly increasing. Stereotactic body radiotherapy (SBRT) is an emerging precision therapy that is being used more frequently in the treatment for unresectable liver metastases. This review focuses on the role of SBRT for liver metastases, principles of treatment, clinical outcomes, toxicity, and optimal patient selection.

Treatment outcomes of stereotactic ablative body radiotherapy on oligometastases from colorectal cancer: early results of a single institution service evaluation

Objective

Stereotactic ablative radiotherapy (SABR) has been suggested to be an effective non-invasive ablative therapy for oligometastases originated from colorectal cancer (CRC). This study aimed to report CRC oligometastases SABR treatment outcomes in terms of overall survival (OS), progression-free survival (PFS) and post-treatment toxicities.

Methods

Treatment records of patients with CRC metachronous oligometastases who underwent SABR at a single institution between February 2015 and December 2018 were retrospectively reviewed. OS and PFS were calculated using Kaplan-Meier statistics and post-RT toxicity data was scored following CTCAE v. 4.0. Analysis of prognostic factors on OS and PFS was performed based on site of primary cancer, types of treatment to primary cancer, number of oligometastases, SABR treatment sites, intervals between treatment to primary cancer and SABR to oligometastases, biological equivalent dose, cumulative gross tumour volume and planning target volume.

Results

75 patients with 86 CRC metachronous oligometastases (including liver, lung, lymph nodes and bone) were included. The median age was 65.5 years (range 42.5-87.2) with a median follow-up of 23.8 months (range 3.1-46.5). The estimated median PFS was 14.6 months (95% CI 9.6-19.6). and estimated median OS was 33.3 months (95% CI 22.9-43.7). Majority of patients tolerated SABR well with the most common acute side-effects of Grade 1 fatigue. No Grade 3 or higher toxicities were reported at any time points.Only SABR treatment sites (p = 0.03) and cumulative volumes of planning target volume (p = 0.02) were found to be statistically significant independent predictors of PFS and OS respectively.

Conclusion

This study showed modest PFS, OS, and post-treatment toxicity outcomes on SABR to metachronous oligometastases from CRC. It has highlighted that cumulative tumour volume may be a stronger prognostic factor of OS comparing to the number of metastases.

Advances in knowledge

There are limited data published on the efficacy and post-treatment toxicity of CRC oligometastases SABR with adequate length of follow-up. Our retrospective study suggests that cumulative tumour volume may be a stronger prognostic factor of OS comparing to the number of oligometastases.

Metastasis-Directed Radiotherapy for Oligoprogressive or Oligopersistent Metastatic Colorectal Cancer

INTRODUCTION

Some patients with cancer may present with progressive or persistent disease at a limited number of sites following a period of treatment response. We evaluated the safety and effectiveness of metastasis-directed radiotherapy (MRT) for oligoprogressive or oligopersistent disease in patients receiving systemic treatment for metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Patients with mCRC who received 5-fluorouracil, leucovorin, and oxaliplatin; 5-fluorouracil, leucovorin, and irinotecan; and/or capecitabine chemotherapy between 2011 and 2020 at a single institution were identified. Then, those who underwent MRT for five or fewer lesion sites while receiving systemic treatment for other metastases were categorized. The primary endpoint was time to change to systemic therapy. Secondary endpoints included MRT-related toxicity, overall survival, and local control.

RESULTS

Among 4157 patients included, 91 (2%) received MRT to limited lesion sites (55 oligoprogressive and 36 oligopersistent) during systemic treatment following a period of treatment response. The median time to change to next-line systemic therapy was 5 months in the overall cohort (measured from the current chemotherapy session) and 9.5 (range, 6.0-40.6) months in the MRT group (measured from the MRT session). No severe toxicity or systemic treatment interruption was observed following MRT. The 1-year local control and overall survival rates were 69% and 99%, respectively.

CONCLUSION

In patients with oligoprogressive or oligopersistent mCRC, MRT may be performed safely in conjunction with systemic treatment to maximize the benefit of systemic therapy and to prolong the time to change to systemic therapy. Further prospective studies should confirm these findings.

Locoregional Therapies for Colorectal Cancer Liver Metastases: Options Beyond Resection

Colorectal cancer was the third most common malignancy worldwide in 2018, and most patients present with or develop distant metastases. Colorectal liver metastases are most commonly observed because of the vascular drainage of the colon and superior rectum. Current guidelines recommend surgical resection as first-line treatment; however, 80% to 90% of patients with colorectal liver metastases are ineligible for primary resection. For patients with unresectable disease, a multidisciplinary treatment approach is favored, incorporating systemic therapy and a toolbox of local ablative therapies. These treatments either aim at cytoreduction to enable a conversion to surgical resectability or control of disease progression and spread. Each of these treatments carries unique outcomes and risk profiles, thereby contributing to an individualized treatment strategy for patients with colorectal liver metastases. This review summarizes evidence on hepatic artery infusion, stereotactic body radiation therapy, thermal ablation, transarterial chemoembolization with drug-eluding beads, and transarterial radioembolization for treatment of colorectal liver metastases. Results of large-scale prospective and retrospective studies and international guidelines are discussed to provide detailed background on the current and prospective use of local ablative techniques in management of colorectal liver metastases.