Differentiating GI Lymphoma from Inflammatory Bowel Disease (IBD) continues to be a challenge in many cats. When ultrasound is suggestive and biopsy is not an option, alternative pathways to diagnosis are needed. The VDI Cancer Panel is a tool, when used in conjunction with an ultrasound, that can help rule-in LSA in the suspected cat. Unfortunately, small cell LSA continued to be a challenging diagnosis on the initial testing. The development of the new Feline GI Lymphoma Panel was aimed at improving the detection of small cell LSA and better separating groups for better sensitivity and specificity in the GI differential.
Table of Contents:
- Biomarker Overview
- Neoplasia Index fGILSA
- Lab Reports
Feline GI Lymphoma Panel is a 4 biomarker panel, 3 of which are integrated into the primary diagnostic algorithm: Neoplasia Index. The markers are:
- Thymidine Kinase Type 1 (TK1): Proliferation Marker
- Haptoglobin (HPT): Inflammatory Marker
- Cobalamin (B12): Essential Vitamin affected by and affecting GI IBD/LSA
- Folate: Essential Vitamin involved in DNA synthesis
TK1, an enzyme responsible for the production of thymidine during cell division, is a proliferation marker of dysregulated replication – a hallmark of cancer. When cell cycles become disrupted/abnormal the TK1 salvage pathway is triggered. In LSA, TK1 values can get exceedingly high.
Cancer is an inflammatory disease. When inflammation is present, cancer may be the cause of that inflammation. The major systemic marker of inflammation in cats is Haptoglobin (HPT). HPT is an acute phase protein, produced by the liver in response to acute phase reactants such as cytokines and interleukins.
Cobalamin is an essential vitamin that plays a number of crucial roles – among them, DNA synthesis. When B12 deficiency exists, cell cycles are incomplete/abnormal resulting in the activation of the TK1 salvage pathway, up-regulating TK1 expression.
The image below shows cycle containing B12 and Folate, and how low levels slow or halt the process.
Folate is also an essential vitamin critical for the proper synthesis of DNA. When folate deficiency occurs, the small folate cycle is affected, impacting cell division and the formation and repair of DNA – leading to cell damage.
Since B12 and Folate are derived from diet, when damage and inflammation in the GI tract occurs, absorption is affected, compounding the issue.
Neoplasia Index™ (NI fGILSA)
The Neoplasia Index (NI) is meant for the diagnostic rule-in of cancer. Developed as a general cancer marker, used in the VDI Cancer Panel, the NI is the primary value used for differential diagnosis of cancer. The NI is unit-less index from 0-10 with 0 being a perfectly normal animal, to 10 being a perfect score for cancer.
Combining independent markers into a unified algorithm improves performance. The base Neoplasia Index incorporates Thymidine Kinase Type 1 and Haptoglobin for general cancer rule-in.
The expanded NI fGILSA, is a specific application for GI lymphoma in cats. It incorporates TK1, HPT, B12, and Age. As you can see below, the NI fGILSA, separates groups remarkably well.
In the untreated cat, the levels of TK1, HPT, and B12 can indicate different disease states commonly associated with that specific marker profile.
Why use Feline GI Lymphoma Panel?
- Application specific Neoplasia Index resulting in better Sensitivity/Specificity, especially with Small Cell LSA
- Indicates if LSA is more likely: Large Cell, Small Cell, or Thoracic
- B12/Folate report provides additional information on status of the GI tract
VDI lab reports are designed to help quickly display answers to the question, and provide interpretive comments. Feline GI Lymphoma Panel reports indicate if the profile is CONSISTENT or INCONSISTENT with LSA and subsequent interpretation of the main components. Below are some examples.
Inflammatory Bowel Disease (IBD)
Negative NI is inconsistent with LSA. Since HPT is abnormal, IBD is indicated.
Large Cell Lymphoma
Positive NI is consistent with LSA. The TK1/HPT/B12 profile is commonly seen in Large Cell LSA.
Small Cell Lymphoma
Positive NI is consistent with LSA. The TK1/HPT/B12 profile is commonly seen in Small Cell LSA.
B12 & Folate (Page 2)
Page 2 of the Feline GI Lymphoma Panel provides further insight into the B12/Folate values along with patient specific dosing guidelines for B12 when values are low.
Feline GI Lymphoma Panel is available immediately on both Frozen serum and Dry Serum Test Kits. Contact VDI with questions – we’re here to help.