|Year : 2019 | Volume
| Issue : 2 | Page : 144-145
MCQs for “Analysis of clinicopathological and immunohistochemical parameters and correlation of outcomes in gastrointestinal stromal tumors”
HS Darling1, S Jayalakshmi1, Pradeep Jaiswal2
1 Department of Radiation Oncology, Artemis Hospital, Gurugram, Haryana, India
2 Department of Surgical Oncology, Command Hospital, Bangalore, Karnataka, India
|Date of Web Publication||2-May-2019|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Darling H S, Jayalakshmi S, Jaiswal P. MCQs for “Analysis of clinicopathological and immunohistochemical parameters and correlation of outcomes in gastrointestinal stromal tumors”. Indian J Cancer 2019;56:144-5
|How to cite this URL:|
Darling H S, Jayalakshmi S, Jaiswal P. MCQs for “Analysis of clinicopathological and immunohistochemical parameters and correlation of outcomes in gastrointestinal stromal tumors”. Indian J Cancer [serial online] 2019 [cited 2019 May 23];56:144-5. Available from: http://www.indianjcancer.com/text.asp?2019/56/2/144/257555
Q1. Which of the following mutations in GIST are mutually exclusive?
- c-kit and PDGFR-α
- c-kit and DOG-1
- DOG-1 and PDGFR-α
- None of the above
Q2. Common sites of GIST in descending order as per incidence are
- Duodenum– stomach–ileum–rectum
Q3. In this study, the sole factor associated with poor recurrence-free survival in multivariate analysis is
- Site of disease
- Extent of resection
- Duration of adjuvant therapy
- Nuclear pleomorphism
Q4. Which of the following are driver mutations?
- c-kit and DOG-1
- PDGFR-α and DOG-1
- c-kit and PDGFR-α
- All of the above
Q5. Choose the false statement pertaining to GIST
- Wild-type GIST is c-kit and PDGFR-α negative
- GISTs are always of gastrointestinal origin
- Wild-type GIST can be DOG-1 positive
- Wild-type GIST can be c-kit driven
Q6. The most important prognostic factors in GIST are all, except
- Tumor size
- Mitotic index
- Lymph node involvement
Q7. Regarding surgery in GIST, true statement is
- Small tumors can be managed with maximal debulking
- Retroperitoneal GISTs are easier to resect
- Wide local excision is the standard of care
- R+ resection is acceptable to save adjacent organs
Q8. DOG-1 is a robust biomarker, it is
- A diagnostic IHC marker of GIST
- An activating mutation in the tyrosine kinase pathway
- The most sensitive marker of GIST
- May be positive in other soft tissue sarcomas
Q9. Adjuvant therapy in an R0 resected gastric GIST of 5 cm would be
- Cytotoxic chemotherapy
- Local radiation therapy
- Tyrosine kinase inhibitor
Q10. The characteristics of PDGFR-α in GIST are all, except
- Is constitutively inactivated
- can be expressed in other soft tissue tumors
- can be detected by IHC
- can be positive along with DOG-1.
Answers and explanations:
- a) c-kit and PDGFR-α
Approximately 17.6% of tumors lacking KIT mutations have activating mutations in a gene encoding a related receptor tyrosine kinase, the platelet-derived growth factor receptor-alpha (PDGFR-α). PDGFR-α mutation leads to the activation of downstream pathways identical to those in KIT-mutant GISTs. Although there is significant functional overlap, KIT and PDGFR-α mutations are mutually exclusive in GISTs.
- b) Stomach–ileum–duodenum–rectum
The majority of cases were gastric in location (47.8%), followed by jejunoileal (18.5%) and duodenum (15.2%).
- d) Nuclear pleomorphism
On multivariate analysis, only nuclearpleomorphism is significantly associated with recurrence.
- c) c-kit and PDGFR-α
More than 90% of GISTs harbor activating KIT mutations. Approximately 17.6% of tumors lacking KIT mutations have activating mutations in a gene encoding a related receptor tyrosine kinase, the platelet-derived growth factor receptor-alpha (PDGFR-α).
- b) GISTs are always of gastrointestinal origin
With the development of highly effective targeted therapies against GISTs, such as imatinib, the prognosis of these patients has significantly improved, which mandates a precise and accurate diagnosis of GISTs to be of utmost importance, especially for the wild-type (c-kit and PDGFR-α negative) GISTs. GIST arising from mesentery and retroperitoneum generally referred to as “extragastrointestinal stromal tumors” (EGISTs) constituted 10%–17.8% of cases in various studies.
- d) Lymph node involvement
The proposed prognostic factor for survival includes tumor size, mitotic index, tumor location, tumor rupture, and kinase mutational status.
- c) Wide local excision is the standard of care
Surgery with negative microscopic margins is the mainstay treatment for resectable nonmetastatic GISTs. Small tumors are usually managed by WLE. The most important factor to prevent recurrence is to prevent tumor rupture or hemorrhage intraoperatively. In half of the patients with retroperitoneal tumors, adjacent organ resection was required suggesting local infiltrating nature of the disease.
- a) A diagnostic IHC marker of GIST
Since DOG1 is specifically expressed by GISTs as compared with ubiquitous positivity of c-kit in many normal cells and other tumors, it is a good supplementary marker.
- d) Tyrosine kinase inhibitor
Imatinib therapy is recommended for tumor larger than 3 cm, especially the tumor adjacent to vital organs and at high risk of recurrence.
- a) Is constitutively inactivated
PDGFR-α mutation leads to the activation of downstream pathways identical to those in KIT-mutant GISTs. Although there is significant functional overlap, KIT and PDGFR-α mutations are mutually exclusive in GISTs. However, PDGFR-α can be expressed in other soft tissue tumors such as synovial sarcoma and leiomyosarcoma and it has a variable expression among GISTs.