Gastric metastasis of small cell lung carcinoma: A rare but noteworthy entity to consider

Abstract

Small cell lung carcinoma (SCLC) is an aggressive malignancy known for its propensity for early and extensive metastatic spread. Gastric metastasis, where cancer cells disseminate from the lung to the stomach, is a rare but increasingly recognized complication of SCLC. This review provides a comprehensive overview of gastric metastasis in SCLC, addressing its clinical significance, diagnostic challenges, management strategies, and prognosis. Additionally, it examines the broader metastatic patterns of SCLC and compares them with other malignancies known for gastric metastasis. Gastric metastasis in SCLC, though infrequent, is clinically significant and often indicates advanced disease with a poor prognosis. SCLC typically metastasizes to the liver, brain, bones, and adrenal glands, with the stomach being an unusual site. The incidence of gastric metastasis ranges from 1% to 5% in autopsy studies, although this may be underestimated due to diagnostic difficulties and asymptomatic early lesions. Diagnosing gastric metastasis presents several challenges, including the asymptomatic nature of many cases, limitations of conventional imaging techniques, and difficulties in distinguishing metastatic lesions from primary gastric cancer via endoscopy. Histopathological diagnosis requires careful examination to identify SCLC cells through their characteristic small cell morphology and neuroendocrine markers. Management of gastric metastasis in SCLC typically involves a multidisciplinary approach. Systemic therapy, primarily chemotherapy, remains the cornerstone of treatment, with palliative care addressing symptoms and complications. Surgical intervention is usually reserved for specific cases requiring symptomatic relief. The prognosis for patients with gastric metastasis from SCLC is generally poor, reflecting the advanced stage of the disease. Median survival is significantly reduced compared to patients without gastric metastasis. This review emphasizes the need for enhanced awareness and early detection to improve patient outcomes and highlights the importance of ongoing research into better diagnostic and therapeutic strategies.

Key Words: Lung cancer; Small cell lung cancer; Gastric metastasis; Metastasis; Rare metastasis

Core Tip: Gastric metastasis in small cell lung carcinoma is a rare but clinically significant complication, often indicative of advanced disease. Due to diagnostic challenges and the typically asymptomatic nature of early gastric lesions, this metastatic involvement may be identified late. A multidisciplinary approach, including systemic therapy and symptomatic management, is essential for optimal patient care.

TO THE EDITOR

In this study we comment on the article by Yang et al[1] published in the recent issue of World Journal of Gastroenterology. Small cell lung carcinoma (SCLC) is a highly aggressive neoplasm characterized by its propensity for early and widespread metastasis[2,3]. SCLC often spreads early through lymphatic and hematogenous routes. Although it is less common, it is possible for SCLC to metastasize to the stomach. This indicates that the cancer has progressed to a stage where it affects other organs beyond the lungs.

Gastric metastasis, wherein cancer cells disseminate from the lungs to the stomach, represents a rare yet increasingly recognized complication of SCLC[3,4]. This review aims to provide an in-depth examination of gastric metastasis in the context of SCLC, encompassing its clinical significance, diagnostic challenges, management strategies, and prognosis, while also considering the broader metastatic patterns of SCLC and other malignancies known for gastric metastasis.

CLINICAL SIGNIFICANCE

Gastric metastasis in SCLC is infrequent but bears considerable clinical significance. SCLC typically metastasizes to the liver, brain, bones, and adrenal glands, with the stomach being an atypical site[5]. Autopsy studies indicate an incidence of gastric metastasis in SCLC ranging from 1% to 5%[6]. This figure may be underestimated due to diagnostic challenges and the often asymptomatic nature of early gastric lesions[4].

The presence of gastric metastasis frequently denotes advanced disease with a poor prognosis. The aggressive progression of SCLC and its tendency for early systemic dissemination often imply widespread metastatic involvement, which complicates treatment and significantly impacts overall survival[5].

Patients often present with a range of clinical symptoms and complications. These may include gastrointestinal issues, such as abdominal pain, nausea, vomiting, dyspepsia, and difficulty in swallowing, along with potential gastrointestinal bleeding, which can manifest as hematemesis or melena. SCLC commonly disseminates to several other sites in addition to gastric metastasis. The liver is one of the most frequent sites of metastasis, and hepatic metastases can lead to symptoms such as hepatomegaly, jaundice, and abdominal pain. Additionally, adrenal involvement is common and patients may present with adrenal insufficiency or incidental adrenal masses[5,7].

While SCLC is one of the less common cancers that metastasizes to the stomach, several other malignancies are known to have a higher incidence of gastric metastasis. Gastric metastasis is relatively common in patients with metastatic breast cancer, particularly in those with the HER2-positive subtype. In advanced melanoma cases, gastric involvement is observed and often correlated with widespread metastatic disease. Renal cell carcinoma may also metastasize to the stomach, presenting as gastric lesions in the context of disseminated disease. Additionally, patients with advanced colorectal cancer may experience gastric metastasis, often as part of a broader pattern of peritoneal dissemination[6,8].

Diagnosis of gastric metastases from SCLC involves several challenges. Patients with gastric metastasis may be asymptomatic or present with nonspecific symptoms, such as abdominal pain, nausea, or dyspepsia, which can be attributed to other conditions, leading to delays in diagnosis. Conventional imaging techniques, including computed tomography scans, may not always detect gastric metastases, especially when lesions are small or exhibit nonspecific features, though advanced imaging modalities, like positron emission tomography scans, offer improved sensitivity but are not always conclusive. Gastrointestinal endoscopy may reveal abnormalities, but distinguishing between primary gastric cancer and metastatic involvement can be challenging, making histopathological examination via biopsy essential for an accurate diagnosis. Accurate identification of SCLC within gastric tissue requires detailed histopathological analysis with small cell morphology and a distinctive immunohistochemical profile, including neuroendocrine markers, such as CD56, synaptophysin, and chromogranin, being crucial for confirming the diagnosis[8,9].

The management of gastric metastasis in SCLC generally involves a multidisciplinary approach. Systemic chemotherapy remains the primary treatment modality due to the widespread nature of SCLC, with regimens typically including platinum-based agents and etoposides. Effective systemic therapy may lead to the regression of gastric metastases, although the response can be variable. While immunotherapy is becoming a standard part of treatment for SCLC, its role in specifically addressing metastatic diseases of the stomach is less clearly defined. The effectiveness of immunotherapy for metastasis in areas like the stomach is still under investigation and depends on various factors, including the tumor's molecular characteristics and the patient’s overall health.

Symptomatic management is also vital for patients with gastric metastasis, involving endoscopic procedures to relieve obstruction, and pharmacological treatments to manage symptoms such as nausea and pain[6,9,10].

In cases of SCLC with stomach metastasis, the role of total gastrectomy is generally very limited. SCLC tends to spread systemically and early, affecting multiple organs, which makes surgery an uncommon approach for metastatic diseases. For patients experiencing significant symptoms due to stomach metastasis, such as obstruction or bleeding, palliative interventions might be considered, but these typically involve less invasive options like bypass surgeries or stenting, rather than complete gastrectomy.

In SCLC with stomach metastasis where there is significant gastric bleeding, the approach focuses on both managing bleeding and addressing the underlying cancer. Firstly, immediate medical intervention is crucial to stabilize the patients. This often involves ensuring hemodynamic stability. In cases of SCLC with metastasis to the gastroesophageal junction, it can lead to significant issues, such as obstruction, difficulty in swallowing, and pain. Endoscopic stenting plays a vital role in managing symptoms and improving the patient’s quality of life by keeping the passage open.

The prognosis of patients with gastric metastasis from SCLC is generally poor, reflecting the advanced stage of the disease. The median survival times are often significantly shorter, compared with those without gastric metastasis. Prognostic factors include the extent of metastatic disease, response to treatment, and the patient’s performance status[11].

CONCLUSION

Gastric metastasis in SCLC, though rare, presents notable diagnostic and management challenges. The presence of gastric metastasis usually signifies advanced disease and necessitates a comprehensive management approach, including systemic therapy, symptomatic care, and, when appropriate, palliative interventions. Enhanced awareness and early detection are crucial for the effective management and improved patient outcomes. Future research on advanced diagnostic techniques and treatment strategies will be essential for optimizing the care of patients with this complex condition.