Oncology Overview with Dr. Siow Tian Rui

Overview of Oncology

• Dr. Siow Tian Rui is a Senior Consultant in Radiation Oncology at the National Cancer Centre Singapore, focusing on Hepato-Pancreato-Biliary, Upper Gastrointestinal, Colorectal, and Thoracic oncology.
• He teaches as an Adjunct Assistant Professor at SingHealth-Duke NUS Medical School.

Learning Outcomes

• Understand the pathophysiology of benign and malignant tumors.
• Identify common symptoms, investigation methods, diagnosis, and staging of cancers.
• Explore mechanisms behind tumor spread and metastasis.
• Compare various cancer therapies: chemotherapy, hormonal therapy, radiation therapy, targeted therapy, and immunomodulatory therapy.

Neoplasm Definition

• Neoplasms are abnormal cellular growths unregulated by normal genetic controls, leading to excessive reproduction.
• Benign tumors are indicated by the suffix "-oma" (e.g., lipoma), while malignant tumors (cancers) use "-carcinoma" (e.g., adenocarcinoma) or "-sarcoma" for connective tissue tumors (e.g., liposarcoma).

Characteristics of Tumors

• Benign Tumors: Resemble normal cells, have slow growth, are usually encapsulated, and localize without spreading.
• Malignant Tumors: Exhibit varying sizes and shapes, rapid and aggressive growth, invade surrounding tissues, and can metastasize to distant sites.

Carcinogenesis

• Carcinogenesis transforms normal cells into cancer cells and is influenced by:
  • Environmental factors, genetic changes, and specific infections.
• Risk factors include genetic predispositions and oncoviruses that alter host DNA.

Symptoms and Effects of Tumors

• Can cause severe fatigue due to inflammatory changes and treatment stress.
• Common complications involve tissue necrosis, bleeding, infections, and paraneoplastic syndromes affecting neurological functions or hormonal balance.

Mechanisms of Tumor Spread

• Invasion: Tumor cells infiltrate adjacent tissues.
• Metastasis: Distant spread through lymphatic or blood vessels, with common sites including the lungs and liver.
• Seeding: Cancer cells spread via body fluids along membranes.

Tumor Staging

• Essential for diagnosis; describes disease extent to guide treatment and prognosis.
• The TMN system categorizes cancer based on:
  • Size of the primary tumor (T).
  • Lymph node involvement (N).
  • Distant metastasis presence (M).

Cancer Treatment Modalities

• Common treatments include surgery, chemotherapy, radiation therapy, and immunotherapy.
• Radiation Therapy Adverse Effects:
  • Bone marrow depression leading to increased infection risk and fatigue.
  • Damage to epithelial cells causing hair loss, mucosal ulcers, and gastrointestinal disturbances.

Chemotherapy

• Utilizes a combination of 2-4 antineoplastic drugs from categories such as antimitotics, antimetabolites, alkylating agents, and antibiotics.
• Primarily effective on rapidly growing cells, administered in cycles.
• Adverse effects resemble those of radiation, affecting bone marrow and causing nausea, alopecia, and potential long-term damage to the lungs, heart, and kidneys.

Targeted Therapy

• A precision medicine approach targeting specific molecules involved in cancer growth and spread.
• Distinguishes itself from standard chemotherapy by targeting specific molecular pathways, resulting in better tolerability and fewer side effects.
• Types include hormone therapy, which utilizes substances like glucocorticoids.