Late small bowel toxicity after aggressive abdominopelvic intensity modulated radiation therapy

Purpose

We retrospectively analyzed late small bowel toxicity in patients who received abdominal or pelvic intensity modulated radiation therapy (IMRT) to the small bowel with a maximum dose greater than the generally accepted maximal tolerable dose of 45 Gy.

Methods and materials

All patients (N = 94) who received IMRT with a point dose of at least 45 Gy to tightly contoured small bowel between 2005 and 2014 at our institution were included. The median prescribed treatment dose was 70.2 Gy. The median follow-up was 20.1 months. Late small bowel toxicity was assessed using the Common Terminology Criteria for Adverse Events Version 3.0. Dosimetric variables and clinical factors were assessed for their relationship to small bowel toxicity.

Results

The median maximal small bowel point dose (D_max) was 6546.5 cGy. The estimated 5-year rates of freedom from at least grade 1, at least grade 2, and at least grade 3 late small bowel toxicity were 72.4% (95% confidence interval [CI], 60.7%-86.5%), 91.9% (95% CI, 84.1%-100%), and 93.6% (95% CI, 86.2%-100%), respectively. One patient (1.1%) developed grade 3 late toxicity, and 2 patients (2.1%) developed grade 4 late toxicity. Use of capecitabine/5-fluorouracil treatment was a significant predictor (P < 0.001) of at least grade 1 and at least grade 2 small bowel toxicity. No other clinical factors were associated with toxicity. None of the dose-volume parameters were significant predictors of small bowel toxicity.

Conclusion

It may be possible with IMRT to deliver high doses to small volumes of small bowel with low rates of significant long-term complications. Further studies should explore tolerable dose-volume relationships in cases in which aggressive abdominal or pelvic treatment may be warranted to treat the underlying malignancy.

Breathing-motion-compensated robotic guided stereotactic body radiation therapy : Patterns of failure analysis

PURPOSE

We retrospectively evaluated the patterns of failure for robotic guided real-time breathing-motion-compensated (BMC) stereotactic body radiation therapy (SBRT) in the treatment of tumors in moving organs.

PATIENTS AND METHODS

Between 2011 and 2016, a total of 198 patients with 280 lung, liver, and abdominal tumors were treated with BMC-SBRT. The median gross tumor volume (GTV) was 12.3 cc (0.1-372.0 cc). Medians of mean GTV BED_{α/β =10 Gy} (BED = biological effective dose) was 148.5 Gy₁₀ (31.5-233.3 Gy₁₀) and prescribed planning target volume (PTV) BED_{α/β =10 Gy} was 89.7 Gy₁₀ (28.8-151.2 Gy₁₀), respectively. We analyzed overall survival (OS) and local control (LC) based on various factors, including BEDs with α/β ratios of 15 Gy (lung metastases), 21 Gy (primary lung tumors), and 27 Gy (liver metastases).

RESULTS

Median follow-up was 10.4 months (2.0-59.0 months). The 2‑year actuarial LC was 100 and 86.4% for primary early and advanced stage lung tumors, respectively, 100% for lung metastases, 82.2% for liver metastases, and 90% for extrapulmonary extrahepatic metastases. The 2‑year OS rate was 47.9% for all patients. In uni- and multivariate analysis, comparatively lower PTV prescription dose (equivalence of 3 × 12-13 Gy) and higher average GTV dose (equivalence of 3 × 18 Gy) to current practice were significantly associated with LC. For OS, Karnofsky performance score (100%), gender (female), and SBRT without simultaneous chemotherapy were significant prognostic factors. Grade 3 side effects were rare (0.5%).

CONCLUSIONS

Robotic guided BMC-SBRT can be considered a safe and effective treatment for solid tumors in moving organs. To reach sufficient local control rates, high average GTV doses are necessary. Further prospective studies are warranted to evaluate these points.

Stereotactic body radiotherapy in oligometastatic prostate cancer patients with isolated lymph nodes involvement: a two-institution experience

OBJECTIVE

Stereotactic body radiotherapy (SBRT) is emerging as a treatment option in oligometastatic cancer patients. This retrospective study aimed to analyze local control, biochemical progression-free survival (b-PFS), and toxicity in patients affected by isolated prostate cancer lymph node metastases. Finally, we evaluated androgen deprivation therapy-free survival (ADT-FS).

METHODS

Forty patients with 47 isolated lymph nodes of recurrent prostate cancer were treated with SBRT. Mostly, two different fractionation schemes were used: 5 × 7 Gy in 23 (48.9 %) lesions and 5 × 8 Gy in 13 (27.7 %) lesions. Response to treatment was assessed with periodical PSA evaluation. Toxicity was registered according to RTOG/EORTC criteria.

RESULTS

With a mean follow-up of 30.18 months, local control was achieved in 98 % of the cases, with a median b-PFS of 24 months. We obtained a 2-year b-PFS of 44 % with 40 % of the patients ADT-free at last follow-up (mean value 26.18 months; range 3.96-59.46), whereas 12.5 % had a mean ADT-FS of 13.58 months (range 2.06-37.13). Late toxicity was observed in one (2.5 %) patient who manifested a grade 3 gastrointestinal toxicity 11.76 months after the end of SBRT.

CONCLUSION

Our study demonstrates that SBRT is safe, effective, and minimally invasive in the eradication of limited nodal metastases, yielding an important delay in prescribing ADT.

The role of stereotactic radiotherapy in the treatment of oligometastases

"Oligometastasis" describes a limited number of metastases arising typically from solid tumors whose behavior suggests an "intermediate" malignant state since it may potentially have a more favorable prognosis. Historically, selected patients with oligometastases often underwent surgical resection since anecdotal evidence suggested it could improve progression-free or overall survival. No prospective randomized trial evidence to date supports survival benefits from surgery. Short courses of highly focused, very high dose radiotherapy (stereotactic radiosurgery; stereotactic body radiotherapy) have emerged as a surgical surrogate to manage oligometastates. For solitary brain metastases, randomized study evidence supports stereotactic radiosurgery as part of their management because of overall survival benefits. Modeled after stereotactic radiosurgery, stereotactic body radiotherapy for extracranial metastases is becoming increasingly common given its efficacy and low toxicity, is an active area of clinical research, and is the subject of this review.

Stereotactic body radiotherapy for oligometastases

The management of metastatic solid tumours has historically focused on systemic treatment given with palliative intent. However, radical surgical treatment of oligometastases is now common practice in some settings. The development of stereotactic body radiotherapy (SBRT), building on improvements in delivery achieved by intensity-modulated and image-guided radiotherapy, now allows delivery of ablative doses of radiation to extracranial sites. Many non-randomised studies have shown that SBRT for oligometastases is safe and effective, with local control rates of about 80%. Importantly, these studies also suggest that the natural history of the disease is changing, with 2-5 year progression-free survival of about 20%. Although complete cure might be possible in a few patients with oligometastases, the aim of SBRT in this setting is to achieve local control and delay progression, and thereby also postpone the need for further treatment. We review published work showing that SBRT offers durable local control and the potential for progression-free survival in non-liver, non-lung oligometastatic disease at a range of sites. However, to test whether SBRT really does improve progression-free survival, randomised trials will be essential.

Stereotactic body radiotherapy for metachronous multisite oligo-recurrence: a long-surviving case with sequential oligo-recurrence in four different organs treated using locally radical radiotherapy and a review of the literature

Stereotactic body radiotherapy (SBRT) for oligometastases represents a recent trend in radiation oncology. While abundant data are available regarding the use of SBRT for the treatment of lung or liver oligometastases from various retrospective series and prospective trials, relatively little information has been accumulated for the treatment of oligometastases at sites other than the lungs and liver, particularly for sequential oligometastases in multiple organs. Oligometastases with primary lesions controlled is called “oligo-recurrence.” We describe herein the case of a lung cancer patient who developed repeated oligo-recurrence at multiple sites that were each controlled by radical radiotherapy and achieved long-term survival and discuss the merits of locally aggressive radiotherapy for this type of disease condition with reviewing the literature. Although further investigation should be undertaken to clarify the benefits, objectives, and methods of SBRT for the treatment of oligometastases, we believe utilization of SBRT may be worthwhile for patients with remote metastases who hope for treatment to acquire better local control and possible longer survival.

The CyberKnife® Robotic Radiosurgery System in 2010

This review provides a complete technical description of the CyberKnife® VSI™ System, the latest addition to the CyberKnife product family, which was released in September 2009. This review updates the previous technical reviews of the original system version published in the late 1990s. Technical developments over the last decade have impacted virtually every aspect of the CyberKnife System. These developments have increased the geometric accuracy of the system and have enhanced the dosimetric accuracy and quality of treatment, with advanced inverse treatment planning algorithms, rapid Monte Carlo dose calculation, and post-processing tools that allow trade-offs between treatment efficiency and dosimetric quality to be explored. This review provides a system overview with detailed descriptions of key subsystems. A detailed review of studies of geometric accuracy is also included, reporting a wide range of experiments involving phantom tests and patient data. Finally, the relationship between technical developments and the greatly increased range of clinical applications they have allowed is reviewed briefly.

Clinical outcome of hypofractionated stereotactic radiotherapy for abdominal lymph node metastases

PURPOSE

We report the medium-term clinical outcome of hypofractionated stereotactic body radiotherapy (SBRT) in a series of patients with either a solitary metastasis or oligometastases from different tumors to abdominal lymph nodes.

METHODS AND MATERIALS

Between January 2006 and June 2009, 19 patients with unresectable nodal metastases in the abdominal retroperitoneal region were treated with SBRT. Of the patients, 11 had a solitary nodal metastasis and 8 had a dominant nodal lesion as part of oligometastatic disease, defined as up to five metastases. The dose prescription was 45 Gy to the clinical target volume in six fractions. The prescription had to be downscaled by 10% to 20% in 6 of 19 cases to keep within dose/volume constraints. The first 11 patients were treated with three-dimensional conformal techniques and the last 8 by volumetric intensity-modulated arc therapy. Median follow-up was 1 year.

RESULTS

Of 19 patients, 2 had a local progression at the site of SBRT; both also showed concomitant tumor growth at distant sites. The actuarial rate of freedom from local progression was 77.8% ± 13.9% at both 12 and 24 months. Eleven patients showed progressive local and/or distant disease at follow-up. The 12- and 24-month progression-free survival rates were 29.5% ± 13.4% and 19.7% ± 12.0%, respectively. The number of metastases (solitary vs. nonsolitary oligometastases) emerged as the only significant variable affecting progression-free survival (p < 0.0004). Both acute and chronic toxicities were minimal.

CONCLUSIONS

Stereotactic body radiotherapy for metastases to abdominal lymph nodes was shown to be feasible with good clinical results in terms of medium-term local control and toxicity rates. Even if most patients eventually show progressive disease at other sites, local control achieved by SBRT may be potentially significant for preserving quality of life and delaying further chemotherapy.

Critical appraisal of volumetric modulated arc therapy in stereotactic body radiation therapy for metastases to abdominal lymph nodes

PURPOSE

A planning study was performed comparing volumetric modulated arcs, RapidArc (RA), fixed beam IMRT (IM), and conformal radiotherapy (CRT) with multiple static fields or short conformal arcs in a series of patients treated with hypofractionated stereotactic body radiation therapy (SBRT) for solitary or oligo-metastases from different tumors to abdominal lymph nodes.

METHODS AND MATERIALS

Fourteen patients were included in the study. Dose prescription was set to 45 Gy (mean dose to clinical target volume [CTV]) in six fractions of 7.5 Gy. Objectives for CTV and planning target volume (PTV) were as follows: Dose(min) >95%, Dose(max) <107%. For organs at risk the following objectives were used: Maximum dose to spine <18 Gy; V(15Gy) <35% for both kidneys, V(36Gy) <1% for duodenum, V(36Gy) <3% for stomach and small bowel, V(15Gy) <(total liver volume--700 cm(3)) for liver. Dose-volume histograms were evaluated to assess plan quality.

RESULTS

Planning objectives on CTV and PTV were achieved by all techniques. Use of RA improved PTV coverage (V(95%) = 90.2% +/- 5.2% for RA compared with 82.5% +/- 9.6% and 84.5% +/- 8.2% for CRT and IM, respectively). Most planning objectives for organs at risk were met by all techniques except for the duodenum, small bowel, and stomach, in which the CRT plans exceeded the dose/volume constraints in some patients. The MU/fraction values were as follows: 2186 +/- 211 for RA, 2583 +/- 699 for IM, and 1554 +/- 153 for CRT. Effective treatment time resulted as follows: 3.7 +/- 0.4 min for RA, 10.6 +/- 1.2 min for IM, and 6.3 +/- 0.5 min for CRT.

CONCLUSIONS

Delivery of SBRT by RA showed improvements in conformal avoidance with respect to standard conformal irradiation. Delivery parameters confirmed logistical advantages of RA, particularly compared with IM.