Systemic Treatments for Advanced Small Bowel Adenocarcinoma: A Systematic Review

Diagnosis and management of gastrointestinal SMARCA4-deficient undifferentiated tumors

SMARCA4-deficient undifferentiated tumors are a rare clinical entity with an aggressive clinical course, poor prognosis, and no standard-of-care therapeutic approach. These have most frequently been documented in the lung and thoracic cavity. There is a growing body of evidence for the role of immunotherapy in SMARCA4-deficient lung cancer, a disease process that historically does very poorly with cytotoxic chemotherapy alone. We present three cases where the primary tumors were instead found within the gastrointestinal system: two originating from the small bowel and one from the esophagus. In all three cases, clinical response was seen with pembrolizumab therapy, with two of the three patients receiving long-term benefit. Our series suggests that anti-PD1 immunotherapy may have promising efficacy for undifferentiated carcinomas of the gastrointestinal tract with SMARCA4 deficiency.

Progress in the Treatment of Small Intestine Cancer

OPINION STATEMENT

Small intestine cancer is rare, accounting for approximately 3% of all gastrointestinal malignancies. The most common histological subtypes include adenocarcinoma, neuroendocrine tumours (NETs) and gastrointestinal stromal tumours (GISTs). In localised disease, surgery remains the mainstay of treatment and the best approach to improve survival. Current treatment for small intestine adenocarcinoma (SIA) is extrapolated from small studies and data from colorectal cancer (CRC). There is limited evidence to guide therapy in the adjuvant setting. However, there are small phase II studies in the advanced setting providing evidence for the role of chemotherapy and immunotherapy. There is also limited evidence assessing the efficacy of targeted therapies. Small intestine NETs are rare, with evidence for somatostatin analogue therapy, particularly in the low to intermediate-grade well-differentiated tumours. Poorly differentiated NETs are generally managed with chemotherapy but have worse outcomes compared with well-differentiated NETs. The management of small intestine GISTs is largely targeting KIT mutations with imatinib. Recent trials have provided evidence for effective therapies in imatinib-resistant tumours and the potential role of immunotherapy. The aim of this article was to review the evidence for the current management and recent advances in the management of small intestine adenocarcinoma, NETs and GISTs.

Evaluation of Systemic Treatments of Small Intestinal Adenocarcinomas: A Systematic Review and Meta-analysis

IMPORTANCE

Although small intestinal adenocarcinomas (SIAs) are rare, they have a poor prognosis, and the optimal treatment strategies are largely unknown. Because of the lack of high-quality evidence, guidelines for colorectal cancer are often followed in the treatment of SIAs.

OBJECTIVE

To review the current evidence regarding survival benefit of systemic therapies, including chemotherapy, targeted agents, and immunotherapy, for patients with SIAs.

DATA SOURCES

Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses, MEDLINE and Embase were searched for articles published from January 1, 2005, until June 1, 2022.

STUDY SELECTION

Retrospective cohort studies and prospective phase 2 or 3 trials describing survival after systemic therapies for patients with SIAs were eligible for inclusion. Assessment of study eligibility was blinded and performed by 3 reviewers.

DATA EXTRACTION AND SYNTHESIS

The reviewers independently extracted data. Random effects, inverse variance, pairwise meta-analyses were performed.

MAIN OUTCOMES AND MEASURES

Primary outcomes were overall survival (OS) and progression-free survival (PFS) of patients with SIAs after systemic therapies. Measures of interest included hazard ratios for survival and median survival times.

RESULTS

Overall, 57 retrospective cohort and phase 2 studies of 35 176 patients were included. Adjuvant chemotherapy, generally fluoropyrimidine-based, was associated with increased OS in stage I to III SIAs (hazard ratio [HR], 0.60; 95% CI, 0.53-0.68), especially in stage III tumors (HR, 0.55; 95% CI, 0.48-0.64), irrespective of tumor localization. Palliative chemotherapy was also associated with an OS benefit (HR, 0.48; 95% CI, 0.40-0.58). Fluoropyrimidine-oxaliplatin combinations were superior to other regimens (OS: HR, 0.54; 95% CI, 0.30-0.99; PFS: HR, 0.46; 95% CI, 0.30-0.71). Furthermore, bevacizumab added to chemotherapy compared with chemotherapy alone was associated with significantly prolonged PFS (HR, 0.62; 95% CI, 0.43-0.89). Immunotherapy showed a 50% overall response rate in previously treated defective mismatch repair tumors.

CONCLUSIONS AND RELEVANCE

In this systematic review and meta-analysis, adjuvant and palliative chemotherapy were both associated with improved survival of patients with SIAs, especially fluoropyrimidine-based regimens and fluoropyrimidine-oxaliplatin combinations. Adding bevacizumab to chemotherapy appears to prolong PFS and deserves further investigation. Immunotherapy seems beneficial and should be considered for patients with defective mismatch repair tumors. International collaborations should be undertaken to confirm and improve efficacy of systemic therapies for patients with SIAs.

Characteristics and outcome of patients with small bowel adenocarcinoma (SBA)

BACKGROUND

Small bowel adenocarcinoma (SBA) remains a rare malignancy accounting for less than 5% of all the gastrointestinal tract cancers. However, only limited data and expert guidelines are available for this entity. As a result, treatment concepts are predominantly derived from colorectal cancer.

METHODS

To substantiate data on the course of disease, diagnosis and treatment of SBA, we performed a population-based analysis from a Bavarian population of 2.2 million people.

RESULTS

We identified 223 patients with SBA. Mean age at diagnosis was 67.8 years and patients were diagnosed rather late (34.5% UICC stage IV). Largest proportion of these patients were diagnosed with adenocarcinoma of the duodenum (132 patients, 59.2%) and most patients were diagnosed with late stage cancer, stage IV (70 patients, 31.4%). With respect to treatment, most patients underwent primary surgery (187 patients, 84.6%). Systemic therapy seemed to have an impact in UICC stage IV patients but not in UICC stage IIB or III. The 5-year survival rate was 29.0%. This was significantly less compared to colon cancer in the same cohort, which was 50.0%. Furthermore, median survival of patients with small bowel cancer was only 2.0 years (95% CI 1.4-2.5) compared to 4.9 years (95% CI 4.8-5.1) of patients with colon cancer.

CONCLUSION

SBA showed a distinct epidemiology compared to colon cancer. Thus, data acquisition particularly on systemic treatment are paramount, with the objective to complement the available guidelines.