Management of brain metastases in lung cancer: evolving roles for radiation and systemic treatment in the era of targeted and immune therapies

Targeting the Hippo pathway to prevent radioresistance brain metastases from the lung (Review)

The prognosis for patients with non‑small cell lung cancer (NSCLC), a cancer type which represents 85% of all lung cancers, is poor with a 5‑year survival rate of 19%, mainly because NSCLC is diagnosed at an advanced and metastatic stage. Despite recent therapeutic advancements, ~50% of patients with NSCLC will develop brain metastases (BMs). Either surgical BM treatment alone for symptomatic patients and patients with single cerebral metastases, or in combination with stereotactic radiotherapy (RT) for patients who are not suitable for surgery or presenting with fewer than four cerebral lesions with a diameter range of 5‑30 mm, or whole‑brain RT for numerous or large BMs can be administered. However, radioresistance (RR) invariably prevents the action of RT. Several mechanisms of RR have been described including hypoxia, cellular stress, presence of cancer stem cells, dysregulation of apoptosis and/or autophagy, dysregulation of the cell cycle, changes in cellular metabolism, epithelial‑to‑mesenchymal transition, overexpression of programmed cell death‑ligand 1 and activation several signaling pathways; however, the role of the Hippo signaling pathway in RR is unclear. Dysregulation of the Hippo pathway in NSCLC confers metastatic properties, and inhibitors targeting this pathway are currently in development. It is therefore essential to evaluate the effect of inhibiting the Hippo pathway, particularly the effector yes‑associated protein‑1, on cerebral metastases originating from lung cancer.

A Cadaveric Case of Bilateral Adrenal Hyperplasia With Lung Cancer: A Paraneoplastic Syndrome?

Bilateral adrenal hyperplasia associated with primary lung cancer may arise from either an adrenocorticotropic hormone (ACTH)-dependent paraneoplastic syndrome or metastatic hyperplasia. Ectopic Cushing's syndrome manifests as a paraneoplastic syndrome characterized by the secretion of ACTH from malignant cells. This secretion can in turn overstimulate the adrenal cortex, resulting in adrenal cortical hyperplasia followed by hypercortisolism. Though rare, lung cancer can metastasize to the adrenal glands bilaterally, occasionally resulting in hemorrhage causing a rapid increase in size. This cadaveric report aims to delineate an unusual case of metastatic lung cancer, presenting with bilateral adrenal hyperplasia and two abdominal aortic aneurysms (AAA). An 84-year-old white male cadaver was dissected during routine coursework. Dissection of the right lung revealed a pale-yellow mass measuring 10.0 x 7.4 x 7.0cm. An irregularly defined, necrotic, ulcerated lesion measuring 5.5 x 4.5 x 3.3cm was evident on the lateral surface of the left shoulder, consistent with a history of metastatic lung carcinoma. Upon abdominal dissection, bilaterally enlarged adrenal glands and two AAAs were observed. These AAAs measured 6.0cm and 11.0cm at their respective widest transverse diameters. The right and left adrenal glands measured 10.0 x 6.5 x 4.5cm and 7.3 x 4.7 x 3.5cm, respectively. We aim to discuss the possible pathophysiological correlation of these unusual findings in this cadaver.

Is two-staged gamma knife surgery a reasonable management option for very large cerebellar metastases? A case series of three patients

OBJECTIVE

Two-staged gamma knife surgery (GKS) is a method that may extend the upper tumor volume limit for using GKS in the management of brain metastases. However, the safety of treating very large posterior fossa lesions with this technique has not been well demonstrated. Therefore, we analyzed our experience in treating cerebellar metastases larger than 12 cm3 with two-staged GKS.

METHODS

Four consecutive patients harboring 12 to 30 cm3 cerebellar metastases scheduled two-staged GKS were included in the study, and all but one patient completed the treatment. The treatment doses were 10-13 Gy. All patients were followed with regular MR imaging and clinical assessments, and the tumor volumes were measured on all treatment and follow-up images.

RESULTS

Tumor progression was not demonstrated in any of the patients. Tumor volumes decreased by, on average, more than half between the two stages. The median survival was 22 months, and no patient died due to intracranial tumor progression. Peritumoral edema at the first GKS resolved in all patients, replaced by asymptomatic mild T2 changes in two of them not requiring any treatment. No radiation-induced complication has developed thus far.

CONCLUSION

Staged GKS seems to be a feasible management option for very large cerebellar metastases.

Immunotherapy and brain metastasis in lung cancer: connecting bench side science to the clinic

Brain metastases (BMs) are the most common form of intracranial malignant neoplasms in adults, with a profound impact on quality of life and traditionally associated with a dismal prognosis. Lung cancer accounts for approximately 40%-50% of BM across different tumors. The process leading to BMs is complex and includes local invasion, intravasation, tumor cells circulation into the bloodstream, disruption of the blood-brain barrier, extravasation of tumor cells into the brain parenchyma, and interaction with cells of the brain microenvironment, among others. Once the tumor cells have seeded in the brain parenchyma, they encounter different glial cells of the brain, as well as immune cells. The interaction between these cells and tumor cells is complex and is associated with both antitumoral and protumoral effects. To overcome the lethal prognosis associated with BMs, different treatment strategies have been developed, such as immunotherapy with immune checkpoint inhibitors, particularly inhibitors of the PD-1/PD-L1 axis, which have demonstrated to be an effective treatment in both non-small cell lung cancer and small cell lung cancer. These antibodies have shown to be effective in the treatment of BM, alone or in combination with chemotherapy or radiotherapy. However, many unsolved questions remain to be answered, such as the sequencing of immunotherapy and radiotherapy, the optimal management in symptomatic BMs, the role of the addition of anti-CTLA-4 antibodies, and so forth. The complexity in the management of BMs in the era of immunotherapy requires a multidisciplinary approach to adequately treat this devastating event. The aim of this review is to summarize evidence regarding epidemiology of BM, its pathophysiology, current approach to treatment strategies, as well as future perspectives.

Five-Year Sustained Complete Remission With Minimal Adverse Effects Following Radiosurgery for 2-cm Brain Metastasis With Deep Eloquent Location From Lung Adenocarcinoma Despite Low Marginal Dose and High 12 Gy Volume

In single-fraction (sf) stereotactic radiosurgery (SRS) for brain metastases (BM) from lung adenocarcinoma (LAC), a marginal dose of ≥22-24 Gy is generally deemed desirable for achieving long-term local tumor control, whereas symptomatic brain radionecrosis significantly increases when the surrounding brain volume receiving ≥12 Gy (V_{12 Gy}) exceeds >5-10 cm³, especially in a deep location. Here, we describe a 75-year-old male with a single LAC-BM of 20 mm in diameter, with a deep eloquent location, which was treated with sfSRS followed by erlotinib, resulting in sustained local complete remission (CR) with minimal adverse radiation effect at nearly five years after sfSRS. The LAC harbored epidermal growth factor receptor (EGFR) mutation. The gross tumor volume (GTV) was defined based on contrast-enhanced computed tomography (CECT) alone. sfSRS was implemented 11 days after planning CECT acquisition. The original GTV had some under- and over-coverage of the enhancing lesion. The D_98% values of corrected GTV (cGTV) (3.08 cm³) and 2-mm outside the cGTV were 18.0 Gy with 55% isodose and 14.8 Gy, respectively. The irradiated isodose volumes, including the GTV, receiving ≥22 Gy and ≥12 Gy were 2.18 cm³ and 14.32 cm³, respectively. Erlotinib was administered 13 days after sfSRS with subsequent dose adjustments over 22 months. There was a remarkable tumor response and subsequent nearly CR of the BM were observed at 2.7 and 6.3 months, respectively, with the tumor remnant being visible as a tiny cavitary lesion located in the cortex of the post-central gyrus at 56.4 months. The present case suggests the existence of: (i) extremely radio- and tyrosine kinase inhibitor (TKI)-sensitive LAC-BM for which sfSRS of ≤18 Gy combined with EGFR-TKI is sufficient for attaining long-term CR; and (ii) long-term brain tolerance following sfSRS despite high 12 Gy volume and deep eloquent location in the late 70s The moderate marginal dose of the GTV, the main location of the BM in the cerebral cortex, and the excellent tumor responses with sufficient extrication from the mass effect may render the BM immune to late adverse radiation effect.

Parotid metastases from primary lung cancer: Case series and systematic review of the features

Most parotid metastases have been reported to come from the head and neck; however, cases metastasized from the lung are extremely rare. Missed diagnoses and misdiagnoses occurred quite a few times. Thus, accurately identifying the clinical features of parotid metastasis of lung cancer is important. However, current studies about this issue are mostly case reports, and little is known about the detailed and systematic aspects. We reported three cases of parotid metastases from lung cancer and then systematically searched similar cases through “Pub-Med” and “Web of Science”. Finally, twenty-three patients were included in the study. Eighty-three percent of which were males, and 19 patients were over 50 years old. In all cases with smoking history mentioned, 93% were smokers. The predominant pathological type was small cell lung cancer (SCLC, 13 patients, 56%). Seventeen combined with other site metastasis, while more than half of which were brain metastases. The survival time ranged from 3months-17years, and as for SCLCs, it was only 3months-40months. It can be concluded that clinical features, such as sex, age, smoking history, pathological types, and metastasis patterns, could provide valuable evidence for diagnosis. The lung seems to be the most common primary site of parotid metastases except for head and neck tumors. The two circumstances, SCLC coexisting with Warthin’s tumor and parotid small cell carcinoma with lung metastasis, should be differentiated from parotid metastasis of lung cancer with caution For cases presented as SCLC, more aggressive strategies, such as chemotherapy with immunotherapy and maintenance therapy, may be more suitable. Due to the greater tendency of brain metastasis in such diseases, whole-brain radiation therapy, stereotactic radiosurgery or prophylactic cranial irradiation should be applied to corresponding patients in time. Additionally, lung cancer parotid metastases may be a marker of poor prognosis.