Current research and treatment for gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have gained considerable research and treatment interest, especially in the last two decades. GISTs are driven by mutations commonly found in the KIT gene and less commonly in the platelet-derived growth factor receptor alpha gene, BRAF gene and succinate dehydrogenase gene. GISTs behave in a spectrum of malignant potential, and both the tumor size and mitotic index are the most commonly used prognostic criteria. Whilst surgical resection can offer the best cure, targeted therapy in the form of tyrosine kinase inhibitors (TKIs) has revolutionized the management options. As the first-line TKI, imatinib offers treatment for advanced and metastatic GISTs, adjuvant therapy in high-risk GISTs and as a neoadjuvant agent to downsize large tumors prior to resection. The emergence of drug resistance has altered some treatment options, including prolonging the first-line TKI from 1 to 3 years, increasing the dose of TKI or switching to second-line TKI. Other newer TKIs, such as sunitinib and regorafenib, may offer some treatment options for imatinib-resistant GISTs. New molecular targeted therapies are being evaluated, such as inhibitors of BRAF, heat shock protein 90, glutamine and mitogen-activated protein kinase signaling, as well as inhibitors of apoptosis proteins antagonist and even immunotherapy. This editorial review summarizes the recent research trials and potential treatment targets that may influence our future patient-specific management of GISTs. The current guidelines in GIST management from Europe, North America and Asia are highlighted.

Nongenomic oestrogen signalling in oestrogen receptor negative breast cancer cells: a role for the angiotensin II receptor AT1

INTRODUCTION

Oestrogens can mediate some of their cell survival properties through a nongenomic mechanism that involves the mitogen-activated protein kinase (MAPK) pathway. The mechanism of this rapid signalling and its dependence on a membrane bound oestrogen receptor (ER), however, remains controversial. The role of G-protein-coupled receptor and epidermal growth factor (EGF) receptor in an ER-independent signalling pathway modulated by oestrogen was investigated.

METHODS

ER-positive and ER-negative breast cancer cell lines (MCF-7 and SKBR3) and primary breast cancer cell cultures were used in this study. Cell proliferation was assessed using standard MTT assays. Protein and cAMP levels were detected by Western blotting and ELISA, respectively. Antigen localization was performed by immunocytochemistry, immunohistochemistry and immunofluorescence. Protein knockdown was achieved using small interfering RNA technologies.

RESULTS

EGF and oestrogen, alone and in combination, induced cell proliferation and phosphorylation of MAPK proteins Raf and ERK (extracellular signal regulated kinase)1/2 in both ER-negative SKBR3 and ER-positive MCF-7 human breast cancer cell lines. Increased Raf phosphorylation was also observed in primary human breast cultures derived from ER-positive and ER-negative breast tumours. Oestrogen induced an increase in intracellular cAMP in ER-negative SKBR3 human breast cancer cells. Oestrogen-mediated cell growth and phosphorylation of MAPK was modified by the EGF receptor antagonist AG1478, the G-protein antagonist pertussis toxin, and the angiotensin II receptor antagonist saralasin. Knockdown of angiotensin II type 1 receptor (AT1) protein expression with small interfering RNA attenuated oestrogen-induced Raf phosphorylation in ER-negative cells. AT1 receptor was found to be expressed in the cell membrane of breast tumour epithelial cells.

CONCLUSION

These findings provide evidence that, in breast cancer cells, oestrogen can signal through AT1 to activate early cell survival mechanisms in an ER-independent manner.

Cryptorchidism: a general surgical perspective

BACKGROUND

The treatment of cryptorchidism has changed, with surgery now advocated before the age of two years. Delayed treatment affects fertility, malignant potential and psychological stress.

AIMS

To assess the pattern of referral of cryptorchid patients to a surgical clinic, management and follow-up.

METHODS

A four-year review of 114 cryptorchid patients examined age at presentation, waiting time, timing of surgery and length of follow-up.

RESULTS

The mean age at presentation to the surgical clinic was 6.7 years (neonatal to 71). The mean age at orchidopexy was 5.6 years. Seventy per cent had a surgical procedure within eight weeks of presentation to a surgeon. Seven per cent were kept under surveillance until a maximum age of three years before orchidopexy was considered. Only 29% proceeded to surgery before the age of two. Seventeen were referred to a paediatric urology unit for further management.

CONCLUSIONS

Orchidopexy seems prudent between one and two years of age. Only one-quarter of patients underwent early orchidopexy. It is vital that it is detected early, by paediatricians at birth or the general practitioners (GPs) at the six-week check up. Prompt referral to a surgeon with a paediatric interest is essential in order to permit surveillance or surgery.

Surgical treatment of gastrointestinal stromal tumors of the stomach: current status and future perspective

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, with the majority found in the stomach. Surgical resection of the primary gastric GISTs with complete resection margin has been the forefront of curative treatment. The indications for surgical resection are usually related to symptomatic gastric GISTs at presentation. Primary gastric GISTs resection performed conventionally through an open surgery can now be frequently achieved by minimal invasive surgery with similar oncological outcome. Surgeon's selection of the type of surgical techniques such as open, laparoscopic and endoscopic resections depends on the site, size and local invasion of gastric GISTs to the adjacent organ. Similarly those factors dictate the extent of gastric resections in the form of wedge, partial or total gastrectomy. All these inherent tumor factors (size and mitotic index), patient factors (older age, male) and surgical factors (incomplete resection margin, tumor rupture or spillage) play an important role in stratifying the malignant potential risk of primary gastric GISTs and their chances of recurrence. The understanding of gene mutation driving the growth of GISTs and the discovery of tyrosine kinase inhibitors (TKIs) has altered the surgical management of advanced and metastatic GISTs. Multi-modal therapy incorporating the surgical resection of GISTs and utilizing the molecular targeted therapy in the adjuvant, neoadjuvant and palliative settings can offer optimal personalized outcome and prolong patient's overall survival (OS).

Current surgical management of duodenal gastrointestinal stromal tumors

Duodenal gastrointestinal stromal tumors (D-GISTs) are uncommon mesenchymal tumors and are managed differently to common duodenal epithelial tumors. They may pose surgical challenges due to their unique but complex pancreaticoduodenal location of the gastrointestinal tract near the ampulla of Vater, pancreas, mesenteric blood vessels, biliary and pancreatic ducts. The surgical management of D-GISTs can be performed safely with good oncological outcomes provided an adequate resection margin can be achieved. The current surgical options of resectable primary D-GISTs varies with increasing complexity depending on the location, size and involvement of surrounding structures such as wedge resection with primary closure, segmental resection with small bowel anastomosis or radical pancreaticoduodenectomy. Laparoscopic approaches have been shown to be feasible and safe with good oncological outcomes in experienced hands. The minimally invasive techniques including robotic-assisted approach will likely increase in the future. D-GISTs have a prognosis comparable to gastric and other small bowel GISTs. However, the heterogeneity of different studies and the limited use of systemic tyrosine kinase inhibitor in the neoadjuvant and adjuvant settings may influence the overall survival of resected D-GISTs. The use of limited resection when condition allows is recommended due to lower surgical morbidity, less postoperative complications and better oncologic outcomes.

Correction to: Nongenomic oestrogen signalling in oestrogen receptor negative breast cancer cells: a role for the angiotensin II receptor AT1

After the publication of this work [1] errors were noticed in the total protein loading controls for Figs. 1C, 2B, 3B and 4B.

Start small and aim big in conducting a basic surgical skills workshop for medical students

Introduction: Medical students (MS) may lack the knowledge and experience in performing basic surgical skills (BSS) when they first commence their postgraduate surgical training. We conducted a pilot BSS workshop with specific learning outcomes for MS. Methods: Our BSS workshop program consisted of reading the pre-workshop online modules, watching the instructional videos of skills demonstration, and completing the pre-workshop multiple-choice questions (MCQ). MS attended the onsite workshop a week later, which consisted of a basic surgical theory lecture, live demonstration of the skills by the teaching faculty and, supervised skills training coupled with feedback. Surgical skills taught were knot tying, suturing techniques, laparoscopic peg transfer, precision cutting, application of endoloop ties. A standardised surgical skills rubric was used to assess the competency and safety of BSS. A post-workshop MCQ was administered to assess the knowledge learned. The criteria for successful completion of BSS were a satisfactory grade in the surgical skills assessment and a pass score in the MCQ. Results: All the participating MS achieved a satisfactory grade in the surgical skills assessment and passed the MCQ. Several pedagogical methods were used to enhance knowledge learning and practical skills competency including a flipped classroom in blended learning, technology-enhanced learning, kinesthetic learning, and providing effective feedback. Conclusion: MS taught in BSS workshop can achieve competency in knowledge, skills, safe attitude and prepare them for future postgraduate surgical training. In the current COVID-19 pandemic, our challenge is to develop similar BSS in a safe environment using technology-enhanced tools such as online instructional videos and online feedback.