Untitled Quiz

Cancer Epidemiology & Carcinogenesis

• Epidemiology studies disease distribution and patterns within populations.
• Informs public health research and policy decisions.
• Forms the basis of evidence-based medicine, identifying risk factors for preventive medicine.
• Data collection is systematic and unbiased.
• Focuses on disease frequency and patterns.
• Uses large databases and complex statistical methods.
• Much cancer data is publicly available.

Most Common Cancers (Worldwide)

• Lung
• Breast
• Colorectal
• Prostate
• Stomach

Top 5 Cancers in the UK

• Breast
• Prostate
• Lung
• Bone
• Melanoma skin cancer

Top 5 Causes of Death

• Lung
• Liver
• Colorectal
• Breast
• Stomach

Incidence & Deaths

• Incidence and deaths are related but provide different information.
• Incidence data shows disease prevalence.
• Incidence also depends on detection methods (e.g., screening).
• Screening can affect incidence statistics.
• Treatment can affect both incidence and death rates.

Relative Survival Chances

• Measured as 1, 5, and 10-year survival rates.
  • Percentage of patients still alive following diagnosis.
• Survival rates vary by cancer type and stage.
• Clinical and research efforts aim to improve survival rates.

Age as a Risk Factor for Cancer

• Childhood tumours often are embryonal (blastomas) or leukaemias—small numbers.
• Young adults see fewer tumours, mainly germ cell.
• Middle to old age, epithelial neoplasms become more common.
• Accumulated genetic changes are a key factor.

Colorectal Cancer: Causes & Risk Factors

• Many factors influence colorectal cancer risk, interacting in complex ways.
• Age is a significant factor, with risk increasing with age.
• Diet (high fat, low fiber) is an important factor, as is a history of inflammatory bowel disease.
• Hereditary predisposition and polyp presence also increase risk.
• Studies indicate a strong role for diet in cancer risk, but this is difficult to isolate with many lifestyle factors involved.
• The EPIC study is large-scale research into cancer and diet.

Lung Cancer

• Similar incidence in women and men, despite varying smoking rates.
• Increased rates in older age groups because of earlier exposure to carcinogens, not higher current smoking.
• The impact of historical smoking rates is notable.

Cervical Cancer

• Australia aims to eliminate cervical cancer by 2035.
• Early detection of pre-cancerous changes (in situ disease) is key to successful prevention and treatment.
• Cervical cancer is largely preventable using screening and prevention efforts.

Carcinogenesis (Initiation, Propagation, Progression)

• Substances capable of causing cancer (carcinogens) have diverse mechanisms.
• Carcinogens act through initiation, propagation, and progression in three steps.
• There are different types and classes dependent on likelihood, classified into groups.
  • Groups based on evidence in humans and animals.

Chemical Carcinogens

• Polycyclic hydrocarbons like tars, cigarette smoke, and cooked foods are associated with skin and lung cancers.
• Aromatic amines, like those from rubber, dyes, and cooked meat, are linked to bladder and other cancers.
• Nitrosamines from tobacco, diet (smoked meats), are carcinogenic and linked to stomach and colorectal cancers, among others.
• Vinyl chloride is linked to angiosarcoma of the liver.
• Alkylating agents such as mustard gas are also carcinogens.

Biological Carcinogens

• Various viruses can cause different types of cancer.
• Human papilloma virus (HPV) is strongly associated with cervical cancers.
• Other viral associations include cancers like liver (Hepatitis B & C) and lymphomas (Epstein-Barr Virus).

Viral Carcinogens

• Various viral infections lead to cancer development in various tissues.

Dietary Factors & Cancer Risks

• High-fat diets are linked to breast and colon cancers.
• High-fiber diets are associated with lowered cancer risk.
• Nitrates and processed meats are linked to stomach and colon cancer.
• Fruit and vegetables, and avoidance of alcohol, are linked to lower cancer risk.
• WHO/IARC classifies red meat as a class 1 carcinogen.

Biological Carcinogens

• Several viruses are known to cause cancer.
• HPV is associated with cervical cancer.
• Other viruses have links to liver, and lymphomas.

Oncogenes

• Mutated proto-oncogenes that promote cell growth and prevent cell death.
• Diverse mechanisms, including altered protein function, amplification and overexpression, are associated with the activation of oncogenes.
• Oncogene activation is a key step in tumor development.

Tumor Suppressor Genes (TSGs)

• Normal genes negatively regulating cell growth and promoting cell death or differentiation.
• Loss of TSG function contributes to unregulated cell growth, a hallmark of cancer.
• Knudson's "two-hit hypothesis" describes how TSG inactivation relates to cancer development.
• Examples of TSGs include p53 and APC.

Hallmarks of Cancer

• Key characteristics found in most cancers, including self-sufficiency in growth signals, insensitivity to anti-growth signals, tissue invasion and metastasis, limitless potential for replication, sustained angiogenesis, and evading apoptosis.

Multistep Nature of Cancer

• Cancer arises from a gradual accumulation of genetic changes, not a single event.
• Accumulation of mutations leads to gradual transformations.
• Benign tumours may be predecessors to malignant cancers, which are characterized as increasingly aggressive and less differentiated.

Histological Differences

• Benign tumors have expansive, non-invasive growth patterns; malignant tumors have expansive, invasive growth.
• Benign tumors tend to resemble the original tissue type structurally versus malignant. Histological characteristics distinguish between them and allow for classification.

Staging

• Stage describes the extent of the disease, both locally and to distant sites.
• Grading and staging are critical in prognosis and determining treatment options.
• TNM system categorizes tumors (T), lymph nodes (N), and distant metastasis (M) to create graded stage descriptors.

Dysplasia

• Abnormal cell growth/differentiation in tissues which sometimes precedes cancer.
• Dysplasia is assessed through tissue examination and serves as a measure of risk.