Team:Czech Republic/Motivation

Motivation

Motivation

Tumor mobility is likely the most significant prognostic factor for all types of cancer. Contained primary tumors often present no symptoms, and if discovered early can be safely removed without needing subsequent chemotherapy. If left untreated, however, primary tumors spread through the lymphatic or blood circulatory systems to other parts of the body. Given enough time, cancer cells undergo transition and take on characteristics of cells from other organs. At this stage, the cells invade compatible organs and secondary tumors called Mets develop.[1] Early mets are less diverse and still present hope for treatment. Later mets, however, are too diverse and are usually associated with terminal diagnoses.

The difference between early stage and late stage diagnosis can be staggering. The table below lists the survival rate differential between early and late diagnosis for common cancer types.

Five-year survival rates by stage for common cancers (www.cancer.org)
Stage Kidney Breast Lung Colorectal Skin Prostate
Stage I 81% 100% 45% 92% 86% 100%
Stage IV 8% 22% 1% 11% 15% 28%

Early detection of cancer and its localization is very difficult. General early detection tests look for specific molecular traces in samples of blood or urine. Such tests usually carry a high rate of false positives and are difficult to calibrate for each individual. In addition, these tests provide limited information regarding the primary and secondary tumor sites. Indeed, the localization of tumors is a real issue. Total body scans are impractical at the necessary resolution level and carcinogenic if applied regularly.

Circulating tumor cells (CTCs) provide an alternate path for tumor detection. These stray cells originate from the tumor site and enter the blood stream after being pushed out from the forefront of the primary tumor. These stray cells are also the first to invade other organs and seed secondary tumors.[2] During the process of detachment and invasion, CTCs undergo several transitions downregulating local adhesion molecules and upregulating distal adhesion molecules and stem cell markers.[3] Deciphering CTC surface markers holds the key to understanding the tumor's ability to invade the host system.

Methods and tools for detecting circulating tumor cells (CTCs) are very limited. CELLSEARCH circulating tumor cell test is the only FDA approved diagnostic method. CTCs are magnetically separated from samples of peripheral blood using the common epithelial marker EpCAM. Subsequently, the cells are stained and individually scanned using an automated positioning and scanning system. Final results are submitted to an expert for review. In clinical practice, however, simple enumeration of CTCs is used most commonly.[4] Another diagnostic waiting for FDA approval is Adnatest, which goes a step further with broad spectrum separation of cells and RT-PCR analysis..[5] Multiple antibodies are used to capture not only EpCAM+ cells but also CA15-3+, Her2new+ and others. RT-PCR kits are targeted at common primary tumors. Customized CTC screens are possible for research purposes only through immunostaining in combination with microdissection...[6][7][8]

The takeaway message is that current CTC diagnostic tests are time-consuming, require advanced training and equipment, are impractical for early diagnosis, and are too broad to yield localization or mobility information.

Reference

  1. ↑ "Metastatic Cancer: Questions and Answers" National Cancer Institute. Retrieved 2008-08-28.
  2. ↑ Gupta, GP; Massagué, J (Nov 17, 2006). "Cancer metastasis: building a framework.". Cell 127 (4): 679–95. doi:10.1016/j.cell.2006.11.001. PMID 17110329.
  3. ↑ Angiogenesis, Metastasis, and the Cellular Microenvironment Circulating Tumor Cells from Patients with Advanced Prostate and Breast Cancer Display Both Epithelial and Mesenchymal Markers Andrew J. Armstrong1,2,3,4,6, Matthew S. Marengo5,7, Sebastian Oltean5,7, Gabor Kemeny5,7, Rhonda L. Bitting1,2,3, James D. Turnbull6, Christina I. Herold1, Paul K. Marcom1,3,6, Daniel J. George1,2,3,4,6, and Mariano A. Garcia-Blanco1,3,5,7 Published OnlineFirst June 10, 2011; DOI: 10.1158/1541-7786.MCR-10-0490
  4. ↑ "An Introduction to the CellSearch™
  5. ↑ "An Introduction to the AdnaTest™
  6. ↑ Yu M. et al. (2011). "Circulating tumor cells: approaches to isolation and characterization". The journal of Cell Biology 192 (3): 373–382. doi:10.1083/jcb.201010021. PMC 3101098. PMID 21300848.
  7. ↑ Nagrath, Sunitha; Sequist, Lecia V.; Maheswaran, Shyamala; Bell, Daphne W.; Irimia, Daniel; Ulkus, Lindsey; Smith, Matthew R.; Kwak, Eunice L.; Digumarthy, Subba; Muzikansky, Alona; Ryan, Paula; Balis, Ulysses J.; Tompkins, Ronald G.; Haber, Daniel A.; Toner, Mehmet (December 2007). "Isolation of rare circulating tumour cells in cancer patients by microchip technology". Nature 450 (7173): 1235–1239. Bibcode:2007Natur.450.1235N. doi:10.1038/nature06385. PMC 3090667. PMID 18097410.
  8. ↑ Wang, Huiqiang; Chen, Nanhai G.; Minev, Boris R.; Zimmermann, Martina; Aguilar, Richard J.; Zhang, Qian; Sturm, Julia B.; Fend, Falko; Yu, Yong A.; Cappello, Joseph; Lauer, Ulrich M.; Szalay, Aladar A. (September 2013). "Optical Detection and Virotherapy of Live Metastatic Tumor Cells in Body Fluids with Vaccinia Strains". PLoS ONE 8 (9): e71105. Bibcode:2013PLoSO...871105W. doi:10.1371/journal.pone.0071105. PMID 24019862.