Stereotactic radiosurgery for the management of brain metastases

A comprehensive review of MR imaging changes following radiosurgery to 500 brain metastases

BACKGROUND AND PURPOSE

Stereotactic radiosurgery is known to control 85%-95% of intracranial metastatic lesions during a median survival of 6-8 months. However, with the advent of newer systemic cancer therapies, survival is improving; this change mandates a longitudinal quantitative analysis of the radiographic response of brain metastases to radiosurgery.

MATERIALS AND METHODS

MR imaging of 516 metastases in 120 patients treated with GK-SRS from June 2006 to December 2009 was retrospectively reviewed. Lesion volume at initial treatment and each follow-up was calculated by using the following formula: length × width × height / 2. Volume changes were correlated with patient demographics, histopathology, and radiation treatment variables.

RESULTS

Thirty-two percent of lesions increased in volume following radiosurgery. Clinically, this translated into 54% of patients having ≥1 of their lesions increase in size. This increase begins at 6 weeks and can last beyond 15 months' post-SRS. Male sex (P = .002), mean voxel dose <37 Gy (P = .009), and initial treatment volume >500 mm(3) (P < .001) are associated with posttreatment increases in tumor size. Median survival following radiosurgery was 9.5 months for patients with all lesions exhibiting stable/decreased volumes, >18.4 months for patients with all lesions exhibiting increased volumes, and 16.4 months for patients with mixed lesional responses.

CONCLUSIONS

Most metastatic lesions are stable or smaller in size during the first 36 months post-SRS. However, a transient increase in volume is seen in approximately one-third of lesions. Sex, treatment dose, initial lesion size, and histopathology all correlate with variations in lesion volume post-SRS. The longer the patient survives, the more likely an increase in lesion size will be seen on follow-up imaging.

Clinical outcomes of stereotactic radiosurgery in the treatment of patients with metastatic brain tumors

BACKGROUND

Stereotactic radiosurgery (SRS) is a form of radiation therapy that delivers a focused, highly conformal dose of radiation to a single volume, while minimizing damage to the adjacent nervous tissue. The efficacy of SRS has been examined in the treatment of patients diagnosed with brain metastases due to the fact that it is capable of targeting any region in the brain and can irradiate multiple tumors in the same treatment setting in a noninvasive fashion.

METHODS

Modern literature was reviewed for studies on SRS in the treatment of patients with brain metastases.

RESULTS

After assessing patient age, Karnofsky Performance Score (KPS), control of primary cancer, presence of extracranial metastases, number of brain metastases, location of brain metastases, and size of brain metastases, SRS offers suitable patients a viable, less invasive treatment option. In patients with 1 to 4 brain metastases who have a KPS ≥70, the addition of SRS to whole-brain radiation therapy (WBRT) produces increased levels of survival and local tumor control when compared with patients treated with WBRT alone. The available evidence suggests that specific patients treated with SRS alone exhibit superior levels of survival and tumor control when compared with patients treated with WBRT alone. Further evidence in the form of a randomized trial is needed to confirm this observation. Questions remain regarding survival and tumor control in patient groups treated with SRS with or without WBRT. Recently published randomized evidence reported a survival advantage in patients treated with SRS alone. These data differ from other previously published randomized evidence, as well as several prospective and retrospective studies, which reported nonsignificant survival differences. Contrasting evidence also exists pertaining to local and distant tumor control, which warrants further investigation into this matter. The available evidence suggests that in patients with 1 to 2 brain metastases, both SRS alone and SRS with WBRT offer equivalent levels of survival when compared with patients treated with surgery with WBRT. Research has been conducted that reports a survival advantage in patients with 1 to 3 brain metastases that were treated with SRS with WBRT.

CONCLUSIONS

SRS can be an advantageous course of treatment in specific patient groups when utilized alone, after surgery, with WBRT, or in combination with either or both of the treatment modalities. Although treatment approaches have been refined, many questions remain unanswered and further clinical evidence is needed to guide physicians in their future treatment decisions regarding treating patients in specific clinical scenarios.

Impact of preexisting tumor necrosis on the efficacy of stereotactic radiosurgery in the treatment of brain metastases in women with breast cancer

BACKGROUND

Breast cancer is the second most common source of brain metastasis. Stereotactic radiosurgery (SRS) can be an effective treatment for some patients with brain metastasis (BM). Necrosis is a common feature of many brain tumors, including BM; however, the influence of tumor necrosis on treatment efficacy of SRS in women with breast cancer metastatic to the brain is unknown.

METHODS

A cohort of 147 women with breast cancer and BM treated consecutively with SRS over 10 years were studied. Of these, 80 (54.4%) had necrosis identified on pretreatment magnetic resonance images and 67 (46.4%) did not. Survival times were computed using the Kaplan-Meier method. Log-rank tests were used to compare groups with respect to survival times, Cox proportional hazards regression models were used to perform univariate and multivariate analyses, and chi-square and Fisher exact tests were used to compare clinicopathologic covariates.

RESULTS

Neurological survival (NS) and survival after SRS were decreased in BM patients with necrosis at the time of SRS compared with patients without necrosis by 32% and 27%, respectively (NS median survival, 25 vs 17 months [log-rank test, P = .006]; SRS median survival, 15 vs 11 months [log-rank test, P = .045]). On multivariate analysis, HER2 amplification status and necrosis influenced NS and SRS after adjusting for standard clinical features, including BM number, size, and volume as well as Karnofsky performance status.

CONCLUSION

Neuroimaging evidence of necrosis at the time of SRS significantly diminished the efficacy of therapy and was a potent prognostic marker.

Multimodality treatment of brain metastases: an institutional survival analysis of 275 patients

Background

Whole brain radiation therapy (WBRT), surgical resection, stereotactic radiosurgery (SRS), and combinations of the three modalities are used in the management of patients with metastatic brain tumors. We present the previously unreported survival outcomes of 275 patients treated for newly diagnosed brain metastases at Cancer Care Northwest and Gamma Knife of Spokane between 1998 and 2008.

Methods

The effects treatment regimen, age, Eastern Cooperative Oncology Group-Performance Status (ECOG-PS), primary tumor histology, number of brain metastases, and total volume of brain metastases have on patient overall survival were analyzed. Statistical analysis was performed using Kaplan-Meier survival curves, Andersen 95% confidence intervals, approximate confidence intervals for log hazard-ratios, and multivariate Cox proportional hazard models.

Results

The median clinical follow up time was 7.2 months. On multivariate analysis, survival statistically favored patients treated with SRS alone when compared to patients treated with WBRT alone (p < 0.001), patients treated with resection with SRS when compared to patients treated with SRS alone (p = 0.020), patients in ECOG-PS class 0 when compared to patients in ECOG-PS classes 2 (p = 0.04), 3 (p < 0.001), and 4 (p < 0.001), patients in the non-small-cell lung cancer group when compared to patients in the combined melanoma and renal-cell carcinoma group (p < 0.001), and patients with breast cancer when compared to patients with non-small-cell lung cancer (p < 0.001).

Conclusions

In our analysis, patients benefited from a combined modality treatment approach and physicians must consider patient age, performance status, and primary tumor histology when recommending specific treatments regimens.

Roles and types of radiation in breast cancer treatment: early breast cancer, locoregionally advanced, and metastatic disease

PURPOSE OF REVIEW

To describe the current role of radiation therapy and specific types of radiation therapy used in the management of early stage, locoregionally advanced, and metastatic breast cancer.

RECENT FINDINGS

The role of radiation therapy in the management of breast cancer has not changed in recent decades, however methods of treatment delivery have advanced considerably. Hypofractionation and accelerated partial breast irradiation, which substantially reduce radiation treatment duration, have emerged as appropriate alternatives to conventional whole breast radiation in select patient subsets, and intensity modulated radiation therapy, breathing-adapted radiation therapy, and prone-positioning technique address challenging anatomic issues and reduce treatment-associated toxicity. Stereotactic radiosurgery and stereotactic body radiation therapy continue to advance the management of distant metastatic disease.

SUMMARY

Radiation therapy plays a significant role in the management of early stage, locoregionally advanced, and metastatic breast cancer. Technological advances are allowing for greater patient convenience and comfort in locoregional radiation therapy delivery and for expanded radiation therapy indications in the setting of metastatic disease.

Therapy and prophylaxis of brain metastases

Metastases of various tumors to the brain account for the majority of brain cancers, and are associated with a poor prognosis. The most common primary sites are lung, breast, skin, kidney and colon; 10-40% of cancer patients develop brain metastases during the course of the disease. The incidence of brain metastasis appears to be rising; reasons may include better therapies for the systemic disease with longer survival of cancer patients but lower efficiency against brain metastases. In this article, we will discuss the conventional treatment with surgery, radiosurgery, radiotherapy and chemotherapy, but also new directions in the management of solid brain metastases. While general therapeutic nihilism should be avoided, it is important to recognize that the number of brain metastases, the extent of the systemic disease and also the tumor type have to be taken into account when choosing individual treatment regimens. Finally, special emphasis will be put on established and future approaches to prevent the disease. We thus aim to provide a framework for treating patients with different presentations of brain metastases, and to highlight important avenues for research.

Evaluation of stereotactic radiosurgery conformity indices for 170 target volumes in patients with brain metastases

A database of clinically approved stereotactic radiosurgery treatment plans was created. One hundred and seventy targets in the database were then retrospectively evaluated using conformity indices suggested by RTOG, SALT‐Lomax and Paddick. Relationships between the three alternative conformity indices were determined. The Paddick index combines the information provided by the RTOG and SALT‐Lomax indices into a single index. The variation in the geometric overlap ratio, which is related to the SALT‐Lomax index, was found to be not clinically relevant for our cohort of patients, and thus the Paddick and RTOG indices can be directly related. It was found that access to a dose volume histogram or dose distribution for a treatment plan renders the RTOG conformity index sufficient for plan quality evaluation.

PACS number: 87.53.Ly

Treatment of brain metastasis from lung cancer

Brain metastases are not only the most common intracranial neoplasm in adults but also very prevalent in patients with lung cancer. Patients have been grouped into different classes based on the presence of prognostic factors such as control of the primary tumor, functional performance status, age, and number of brain metastases. Patients with good prognosis may benefit from more aggressive treatment because of the potential for prolonged survival for some of them. In this review, we will comprehensively discuss the therapeutic options for treating brain metastases, which arise mostly from a lung cancer primary. In particular, we will focus on the patient selection for combined modality treatment of brain metastases, such as surgical resection or stereotactic radiosurgery (SRS) combined with whole brain irradiation; the use of radiosensitizers; and the neurocognitive deficits after whole brain irradiation with or without SRS. The benefit of prophylactic cranial irradiation (PCI) and its potentially associated neuro-toxicity for both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) are also discussed, along with the combined treatment of intrathoracic primary disease and solitary brain metastasis. The roles of SRS to the surgical bed, fractionated stereotactic radiotherapy, WBRT with an integrated boost to the gross brain metastases, as well as combining WBRT with epidermal growth factor receptor (EGFR) inhibitors, are explored as well.

Factors related to the local treatment failure of γ knife surgery for metastatic brain tumors

PURPOSE

Radiosurgery (RS) is regarded as a standard therapy for metastatic brain tumors, but local failure requiring repeated therapy for the same lesion remains an unsolved problem. The authors analyzed outcomes of gamma knife surgery (GKS) for metastatic lesions to identify factors of local treatment failure.

MATERIALS AND METHODS

The hospital records of 103 patients with a metastatic brain tumor and monitored for more than 6 months were analyzed. Lesion response to RS was analyzed in 77 patients with available gamma plan data. Local treatment failure was defined as lesion regrowth or repeat GKS within 6 months. In cases with multiple lesions, largest masses were evaluated. Primary sites, metastatic location, Karnofsky scale, tumor size, number of metastatic lesions, and various radiosurgical prescription parameters, namely, Paddick's conformity index (CI), Radiation Therapy Oncology Group (RTOG)-CI, and gradient index, were analyzed.

RESULTS

Of the 103 study subjects, 58 were male and 45 were female. Primary sites were lung (n = 58), breast (n = 12), colon (n = 6), kidney (n = 7), rectum (n = 6), and others (n = 14). Median survival duration from the diagnosis of brain metastasis was 25 months. Local treatment failure occurred in 14 of 77 the patients (77 lesions) with available gamma plan data. A lung cancer primary site was found to have a lower GKS failure rate than a breast or a renal site (p < 0.05). Lesions with a high Paddicks' CI or a low RTOG-CI had a higher rate of treatment failure (p < 0.05). Multivariate analysis revealed that primary tumor site and Paddick's CI were related to treatment failure (p < 0.05).

CONCLUSION

Brain metastases from renal and breast cancers had higher rates of local GKS treatment failure than those from lung cancer. Furthermore, high Paddick's CI revealed higher rate of local recurrence, and was not contributory to prevent local treatment failure. However, the enlargement of the diameter of the tumor after RS in the early follow-up period does not necessarily represent the poor outcome or need of retreatment.

Phase I trial of simultaneous in-field boost with helical tomotherapy for patients with one to three brain metastases

PURPOSE

Stereotactic radiosurgery is an alternative to surgical resection for selected intracranial lesions. Integrated image-guided intensity-modulated-capable radiotherapy platforms such as helical tomotherapy (HT) could potentially replace traditional radiosurgery apparatus. The present study's objective was to determine the maximally tolerated dose of a simultaneous in-field boost integrated with whole brain radiotherapy for palliative treatment of patients with one to three brain metastases using HT.

METHODS AND MATERIALS

The inclusion/exclusion criteria and endpoints were consistent with the Radiation Therapy Oncology Group 9508 radiosurgery trial. The cohorts were constructed with a 3 + 3 design; however, additional patients were enrolled in the lower dose tolerable cohorts during the toxicity assessment periods. Whole brain radiotherapy (30 Gy in 10 fractions) was delivered with a 5-30-Gy (total lesion dose of 35-60 Gy in 10 fractions) simultaneous in-field boost delivered to the brain metastases. The maximally tolerated dose was determined by the frequency of neurologic Grade 3-5 National Cancer Institute Common Toxicity Criteria, version 3.0, dose-limiting toxicity events within each Phase I cohort.

RESULTS

A total of 48 patients received treatment in the 35-Gy (n = 3), 40-Gy (n = 16), 50-Gy (n = 15), 55-Gy (n = 8), and 60-Gy (n = 6) cohorts. No patients experienced dose-limiting toxicity events in any of the trial cohorts. The 3-month RECIST assessments available for 32 of the 48 patients demonstrated a complete response in 2, a partial response in 16, stable disease in 6, and progressive disease in 8 patients.

CONCLUSION

The delivery of 60 Gy in 10 fractions to one to three brain metastases synchronously with 30 Gy whole brain radiotherapy was achieved without dose-limiting central nervous system toxicity as assessed 3 months after treatment. This approach is being tested in a Phase II efficacy trial.

Recent advances in radiotherapy

Radiation therapy has come a long way from treatment planning based on orthogonal radiographs with large margins around tumours. Advances in imaging and radiation planning software have led to three-dimensional conformal radiotherapy and, further, to intensity modulated radiotherapy (IMRT). IMRT permits sparing of normal tissues and hence dose-escalation to tumours. IMRT is the current standard in treatment of head and prostate cancer and is being investigated in other tumour sites. Exquisitely sculpted dose distributions (increased geographical miss) with IMRT, plus tumour motion and anatomical changes during radiotherapy make image guided radiotherapy an essential part of modern radiation delivery. Various hardware and software tools are under investigation for optimal IGRT.