Prophylactic cranial irradiation as a component of intensified initial treatment of locally advanced non-small cell lung cancer

[Research Progress on Risk Factors of Brain Metastasis in Non-small Cell Lung Cancer]

Brain metastasis of non-small cell lung cancer (NSCLC) is a common treatment failure mode, and the median survival time of NSCLC patients with brain metastasis is only 1 mon-2 mon. Prophylactic cranial irradiation (PCI) can delay the occurrence of brain metastasis, but the survival benefits of NSCLC patients are still controversial. It is particularly important to identify the patients who are most likely to benefit from PCI. This article reviews the high risk factors of brain metastasis in NSCLC.
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Treatment planning of volumetric modulated arc therapy and positioning optimization for hippocampal-avoidance prophylactic cranial irradiation

BACKGROUND

Hippocampal-avoidance prophylactic cranial irradiation (HA-PCI) offers potential neurocognitive benefits but raises technical challenges to treatment planning. This study aims to improve the conventional planning method using volumetric modulated arc therapy (VMAT) technique and investigate a better patient's head positioning to achieve a high quality of HA-PCI treatment plans.

METHODS

The improved planning method set a wide expansion of hippocampus as a special region for dose decline. The whole brain target was divided into two parts according to whether the slice included hippocampus and their optimization objectives were set separately. Four coplanar full arcs with partial field sizes were employed to deliver radiation dose to different parts of the target. The collimator angle for all arcs was 90°. Tilting patient's head was achieved by rotating CT images. The improved planning method and tilted head positioning were verified using datasets from 16 patients previously treated with HA-PCI using helical tomotherapy (HT).

RESULTS

For the improved VMAT plans, the max and mean doses to hippocampus were 7.88 Gy and 6.32 Gy, respectively, significantly lower than those for the conventional VMAT plans (P < 0.001). Meanwhile, the improved planning method significantly improved the plan quality. Compared to the HT plans, the improved VMAT plans result in similar mean dose to hippocampus (P > 0.1) but lower max dose (P < 0.02). Besides, the target coverage was the highest for the improved VMAT plans. The tilted head positioning further reduced the max and mean doses to hippocampus (P < 0.05), significantly decreased the max dose to lens (P < 0.001) and resulted in higher plan quality as compared to nontilted head positioning.

CONCLUSIONS

The improved planning method enables the VMAT plans to meet the clinical requirements of HA-PCI treatment with high plan quality and convenience. The tilted head positioning provides superior dosimetric advantages over the nontilted head positioning, which is recommended for clinical application.

Is a selective brain (18)F-FDG PET/CT study profitable in patients with small cell lung cancer?

AIM

To evaluate the diagnostic yield of a selective brain (18)F-FDG PET/CT in neurologically asymptomatic patients with small cell lung cancer.

MATERIAL AND METHODS

Twenty-one neurologically asymptomatic patients referred to our service between July 2008 and December 2009 for staging of small cell lung cancer were included in the study. All underwent a standard (18)F-FDG PET/CT study followed by a selective brain PET/CT. The neurological findings were confirmed by CT scan with intravenous contrast, MRI or minimum clinical follow-up of 6 months. The brain PET/CT was considered positive if any alteration was observed in the FDG distribution that was not related with previously known benign lesion in the CT image.

RESULTS

Brain metastases were detected in 5 of the 21 patients (23.8%), these being correctly classified in 3 of them by the selective brain PET/CT. The stage was upgraded in one of them with the selective brain study. Only one patient showed a hypermetabolic lesion in the PET images in relationship to the lesions observed in the CT images. Sensibility, specificity, positive predictive value and negative predictive value were 60, 100, 100 and 88.89%, respectively.

CONCLUSION

Hypometabolic areas in the cerebral parenchyma are frequently associated to metastatic lesions in patients with small cell lung cancer. The selective brain PET/CT in these patients allows correct staging and early treatment of unsuspected metastasis.

Behaviour and survival of high-grade neuroendocrine carcinomas of the lung

INTRODUCTION

Large-cell neuroendocrine carcinoma is an aggressive variant of large-cell carcinoma of the lung, which has poor survival in most series, resembling that of small-cell lung carcinoma. We report our retrospective assessment of surgically-resected cases of both tumours.

METHODS

33 large-cell neuroendocrine carcinomas and 16 peripheral small-cell lung carcinomas were reassessed retrospectively. Survival rates of both tumours in surgically-resected cases were calculated and compared using Kaplan-Meier survival curves and Log Rank test, respectively.

RESULTS

In large-cell neuroendocrine carcinomas, there were 25 patients with pathologic stage I, 4 with pathologic stage II and 4 with pathologic stage III. In small-cell lung carcinomas, there were 6 patients with pathologic stage I, 3 with pathologic stage II and 7 with pathologic stage III. 12% of large-cell neuroendocrine carcinomas and 62.5% of small-cell lung carcinomas were of advanced disease. The mean follow-up was 89 months. The actuarial survival for the 2 groups was not significantly different.

CONCLUSION

Large-cell neuroendocrine carcinomas of the lung have poor prognosis even in early stages, with survival rates similar to that of small-cell lung carcinomas.

Cognitive Sparing during the Administration of Whole Brain Radiotherapy and Prophylactic Cranial Irradiation: Current Concepts and Approaches

Whole brain radiotherapy (WBRT) for the palliation of metastases, or as prophylaxis to prevent intracranial metastases, can be associated with subacute and late decline in memory and other cognitive functions. Moreover, these changes are often increased in both frequency and severity when cranial irradiation is combined with the use of systemic or intrathecal chemotherapy. Approaches to preventing or reducing this toxicity include the use of stereotactic radiosurgery (SRS) instead of WBRT; dose reduction for PCI; exclusion of the limbic circuit, hippocampal formation, and/or neural stem cell regions of the brain during radiotherapy; avoidance of intrathecal and/or systemic chemotherapy during radiotherapy; the use of high-dose, systemic chemotherapy in lieu of WBRT. This review discusses these concepts in detail as well as providing both neuroanatomic and radiobiologic background relevant to these issues.

Risk of cerebral metastases for postoperative locally advanced non-small-cell lung cancer

BACKGROUND

Cerebral metastases are the main determining factor in the failure of locally advanced non-small-cell lung cancer (NSCLC) management. Our study assessed the risk factors of brain metastases in patients with postoperative, locally advanced NSCLC. Implications for PCI treatment are discussed.

METHODS

Two hundred twenty-three patients treated with surgical resection for stage III-N2 NSCLC were retrospective analyzed to elucidate risk factors for development of brain metastases, and to establish a mathematical model.

RESULTS

Median survival time for this patient population was 29.5 months. Frequency of brain metastases in the entire patient population was 38.1% (85/223). Frequency of brain metastases in patients with single mediastinal lymph-node region with metastases at 1, 2, and 3 years was 5.6%, 14.0%, and 19.0%, respectively. The frequency of brain metastases in patients with multiple mediastinal lymph-node regions with metastases was 31.8%, 60.3%, 68.0%, respectively (P<0.001). The frequency of brain metastases among patients with mediastinal metastasis number less than 4, 4-6, and more than 6 was significantly different (P<0.001). There were also significant differences in brain metastases frequency between patients with complete versus incomplete resection (P=0.001), and patients with non-squmous versus squamous (P=0.029), and patients administered adjuvant chemotherapy versus none (P=0.032).

CONCLUSION

A mathematical model to predict brain metastases risk was developed. It can aid in selection of patients with locally advanced NSCLC for PCI in clinical trails.

Pulmonary large cell neuroendocrine carcinoma: its place in the spectrum of pulmonary carcinoma

In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) as a variant of large cell carcinoma. The World Health Organization categorization not only classified histologic types of large cell carcinomas of the lung in detail, but also revealed that histologic subtypes of lung carcinomas were closely related to the prognosis of patients with those carcinomas. Large cell neuroendocrine carcinomas are common tumors that are now more frequently diagnosed by pathologists as recognition of LCNEC improves. Since the first report of LCNEC in 1991, many authors have reported that LCNECs are aggressive tumors and that patients with LCNECs have a very poor prognosis. Although LCNEC is categorized as a variant of large cell carcinoma, the biological behaviors of LCNEC tumors resemble those of small cell lung carcinomas, and LCNEC reveals the feature of a high-grade neuroendocrine tumor. Because patients with LCNEC have a poor prognosis, surgery alone is not sufficient. Multimodality therapies (including adjuvant chemotherapy) appear to be promising for the improvement of the prognosis in patients with LCNEC, even if the pathologic stage is IA, and should be evaluated further in larger multi-institutional trials.