Stereotactic ablative radiotherapy for oligometastatic disease in liver

Stereotactic radiotherapy for liver oligometastases

The liver is the first metastatic site in 15–25% of colorectal cancer patients and one of the first metastatic sites for lung and breast cancer patients.

A computed tomography (CT ) scan with contrast medium is a standard procedure for assessing liver lesions but magnetic resonance imaging (MRI) characterizes small lesions better thanks to its high soft-tissue contrast. Positron emission tomography with computed tomography (PET-CT ) plays a complementary role in the diagnosis of liver metastases. Triphasic (arterial, venous and time-delayed) acquisition of contrast-medium CT images is the first step in treatment planning. Since the liver exhibits a relatively wide mobility due to respiratory movements and bowel filling, appropriate techniques are needed for target identification and motion management. Contouring requires precise recognition of target lesion edges. Information from contrast MRI and/or PET-CT is crucial as they best visualize metastatic disease in the parenchyma. Even though different fractionation schedules were reported, doses and fractionation schedules for liver stereotactic radiotherapy (SRT ) have not yet been established. The best local control rates were obtained with BED₁₀ values over 100 Gy. Local control rates from most retrospective studies, which were limited by short follow-ups and included different primary tumors with intrinsic heterogeneity, ranged from 60% to 90% at 1 and 2 years. The most common SRT-related toxicities are increases in liver enzymes, hyperbilirubinemia and hypoalbuminemia. Overall, late toxicity is mild even in long-term follow-ups.

Stereotactic Ablative Radiation Therapy for Unresectable Colorectal Oligometastases

Purpose

Patients with oligometastatic colorectal cancer have demonstrated excellent clinical outcomes with surgical resection of hepatic and pulmonary metastases. Stereotactic ablative radiation therapy (SABR) has emerged as an alternative local therapy for nonsurgical candidates. Herein, we report the oncologic and patient-reported quality-of-life (PR-QoL) outcomes for a subset of patients with oligometastatic colorectal cancer who were treated in a prospective phase 2 multicenter clinical trial.

Methods and materials

Patients with a pathologically proven diagnosis of oligometastatic colorectal cancer were enrolled as part of a prospective study. SABR dose and fractionation schedules were dependent on the lesion location and size. Patient follow-up occurred 6 weeks after completion of SABR and at 3-month intervals for the following 3 years. Patients received the Functional Assessment of Cancer Therapy-General questionnaire at baseline and at each follow-up visit to assess PR-QoL. The total Functional Assessment of Cancer Therapy-General questionnaire scores were compared with those from baseline using the Wilcoxon signed rank test. Overall survival, local progression-free survival (PFS), and distant PFS were calculated using the Kaplan-Meier estimation to the date of the last follow-up visit/death or local/distant failure.

Results

A total of 31 patients with oligometastatic colorectal cancer with 1 (71.0%), 2 (16.1%), 3 (3.2%), 4 (3.2%), or 5 (6.5%) metastatic lesions were identified. After a median follow-up time of 50.1 months, the median OS from the time of completion of the SABR was 53.9 months (95% confidence interval, 23.2-84.6), and the 5-year OS, local PFS, and distant PFS were 45%, 83%, and 27%, respectively. Acute grade 2+ toxicity was 9.7% (pain, nausea, fatigue) and late grade 3+ toxicity (small bowel obstruction) was 3.2% with no significant change in PR-QoL in the year after SABR.

Conclusions

This subset analysis of a prospective phase 2 study demonstrates that SABR is a safe and effective treatment option for patients with unresectable oligometastic colorectal cancer. In addition, SABR of oligometastatic disease preserves PR-QoL.

Use of Indirect Target Gating in Magnetic Resonance-guided Liver Stereotactic Body Radiotherapy: Case Report of an Oligometastatic Patient

The case of a 73-year-old woman affected by anal canal cancer with concomitant liver metastases is presented here. The patient was addressed to stereotactic body radiotherapy (SBRT) on two hepatic secondary lesions after the first radiochemotherapy treatment of the primary tumor. A Tri-60-Co magnetic resonance hybrid radiotherapy unit was used for SBRT treatment delivery. Both liver lesions were not clearly visible on the setup magnetic resonance imaging (MRI) due to their limited dimensions (maximum diameter 13 mm); however, the presence of two cysts adjacent to the metastases allowed the use of an indirect target gating approach. Treatment was delivered in deep inspiration breath-hold conditions using the visual feedback technique for breathing control optimization. Post radiotherapy imaging assessed the complete response.

[Local ablative radiotherapy of oligometastatic colorectal cancer]

BACKGROUND

Colorectal cancer (CRC) often presents as oligometastatic disease. Currently available intensive systemic treatment regimens, including combination chemotherapy and molecular targeted agents, result in tumor response and transient to long-term disease control in a high percentage of patients, thus raising the question of further management. Secondary resection and ablation, e.g. by surgery or radiofrequency may contribute to long-term survival and even be curative or at least allow a relevant chemotherapy-free interval. These approaches are often limited by the anatomical site, invasiveness and morbidity of the respective procedure. With stereotactic body radiotherapy (SBRT) metastases can be treated with very high efficiency in only a few sessions and achieving long-term control.

OBJECTIVES

Identification of clinical studies investigating the use of SBRT for treatment of oligometastases in CRC patients. Control rates in liver and lung metastases and survival after SBRT. Toxicity and side effects of the treatment.

MATERIAL AND METHODS

A literature search was carried out for prospective and retrospective studies on local SBRT.

RESULTS AND CONCLUSION

The SBRT procedure has become a valid treatment option for patients with oligometastatic CRC and should also be considered in clinical practice as an alternative to surgical treatment of metastases or other local ablative techniques.