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The Critical Role of Tumor Typing in Cancer Treatment and the Expanding Horizons of Molecular
Oncology

Omer Faruk Bayrak , Elif Duz , Aysegul Kuskucu , Didem Seven , Oznur Suakar 1
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1 Yeditepe University School of Medicine Department of Medical Genetics
Keywords: tumor typing, personalized medicine, molecular oncology, targeted therapy, liquid biopsy

Cancer remains one of the most complex and heterogeneous diseases affecting humanity. Traditional classifications
of cancer have relied heavily on histological and anatomical characteristics; however, with the advent of molecular
biology and genomics, it has become clear thattumors with a similar appearance under a microscope can behave
very differently at the molecular level. This realization has led to the development and growing importance of tumor
typing, also referred to as molecular subtyping. Tumor typing involves analyzing the genetic, epigenetic, transcriptomic,
and proteomic characteristics of a tumor to betterunderstand its behavior, prognosis, and likely response to specific
therapies. This molecular classification has transformed modern oncology, paving the way for personalized and
precision medicine, where treatments are tailored to the unique biological profile of each patient's cancer.

Why Tumor Typing Matters in Modern Oncology:

1. Personalized Treatment Approaches
Molecular tumor typing enables the design of patient-specific treatment plans. By identifying mutations, gene
expression patterns, or disruptions in signaling pathways driving a particular tumor, oncologists can choose therapies
that specifically target these alterations. For instance, in non-small cell lung cancer (NSCLC),tumors with EGFR mutations
respond well to EGFR tyrosine kinaseinhibitors (TKIs). Similarly, HER2-positive breast cancers can beeffectively treated
with monoclonal antibodies like trastuzumab.

2. Predictive Value for Treatment Response
Not all tumors respond the same way to standard chemotherapy orradiotherapy. Tumor typing allows for the
identification of predictivebiomarkers, which indicate how likely a tumor is to respond to certaintreatments. For
example, tumors exhibiting microsatellite instability(MSI-H) are more likely to benefit from immune checkpoint
inhibitors,whereas those with KRAS mutations in colorectal cancer may not respondto EGFR inhibitors.

3. Prognostic Information
Molecular features of tumors can provide critical prognosticinformation, offering insights into how aggressive a cancer
might be, as well as the likelihood of recurrence. Breast cancer subtypes such as Luminal A, Luminal B, HER2-enriched,
and Basal-like (triple-negative)have distinct prognoses and clinical behaviors, guiding decisions on the intensity and
duration of treatment.

4. Guiding Early Detection and Prevention Understanding the molecular pathways involved in cancer initiation and
progression can lead to the development of early detection tools, such as biomarker-based screening tests. For example,
the presence of HPV DNA is a key marker in screening for cervical cancer, while circulating tumor DNA (ctDNA) is being
explored for early detection of colorectal and lung cancers.

5. Avoiding Overtreatment In some cases, knowledge of a tumor's molecular profile helps clinicians avoid unnecessary
aggressive treatments. For instance, in early-stage prostate cancer, identifying low-risk molecular signatures may
support a decision for active surveillance rather than immediate surgery or radiation, thereby preserving quality of life.

Expanding Frontiers: Future Perspectives in Molecular Biology of Cancer the future of oncology is inseparably linked
to advances in molecular biology. As our ability to analyze tumors at the molecular level improves, new tools and
therapeutic approaches are emerging that hold the promise of transforming cancer care.

1. Liquid Biopsy and Non-Invasive Diagnostics
One of the most exciting advancements is the development of liquid biopsy, which involves detecting cancer-related
biomarkers in bodyfluids, primarily blood. By analyzing circulating tumor cells (CTCs), ctDNA, or exosomes, liquid

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