Week 3

• Many cancers are diagnosed when it’s too late because early cancers may not have any symptoms.
• Screening tests and programs are preventative measures aimed at detecting a potential health problem or disease in someone that doesn’t yet have signs or symptoms.
• The target population for screening tests and programs is different according to the type of disease.
• The Wilson criteria for cancer screening are: the condition is an important health problem, its natural history is well understood, it is recognisable at an early stage, treatment is better at an early stage, a suitable test exists, an acceptable test exists, and adequate facilities exist to cope with abnormalities detected.
• Cervical cancer screening in the UK is done on women aged 25-64 years at 3-5 yearly intervals with a 'Pap' smear.
• Breast cancer screening in the UK is done on women aged 50-70 years every 3 years, based on mammography, which is aimed at detecting microcalcification or distortions.
• Bowel cancer screening in the UK is done on men and women aged 50-69 years every 2 years, based on Faecal Occult Blood (FOB) testing.
• Neoplasia refers to 'new growth' where cellular proliferation and growth occur without external stimulus, resulting in an abnormal mass of cells called a neoplasm or tumour
• Neoplasms can be benign or malignant, with malignant neoplasms being called cancer
• Loss of normal growth control leads to uncontrolled growth in cancer cell division
• Cancer cell division is a result of mutations, with the first mutation leading to cell damage and no repair, followed by subsequent mutations causing uncontrolled growth
• Normal growth involves processes like cell migration in the dermis, dividing cells in the basal layer, and shedding of dead cells from the outer surface in the epidermis
• Invasion and metastasis in cancer involve cancer cells invading surrounding tissues and blood vessels, being transported by the circulatory system to distant sites, and reinvading and growing at new locations
• Malignant tumours (cancer) invade neighboring tissues, enter blood vessels, and metastasize, while benign tumours (not cancer) grow only locally and cannot spread by invasion or metastasis
• Carcinoma in situ refers to severe dysplasia where there is disordered growth but the changes do not penetrate the basement membrane, indicating a pre-invasive stage
• The aetiology and pathogenesis of cancer involve a multifactorial and multistep journey with both intrinsic (genetic, immune) and extrinsic (environmental, chemical, infectious, drugs) causes
• Factors like viruses, bacteria, heredity, diet, hormones, radiation, and chemicals are associated with cancer, with most cases having an unknown cause
• Tobacco and obesity are significant risk factors for cancer, with smoking being the biggest cause of cancer worldwide and excess weight being the second biggest preventable cause in the UK
• Alcohol consumption is linked to 7 types of cancer including breast, mouth, and bowel cancer
• Radiation, both low-strength (annual sunshine) and high-strength (X-ray dose), is associated with cancer incidence, with UV radiation contributing to skin cancer
• Mutations in DNA, including additions, deletions, and single base changes, affect oncogenes and tumour suppressor genes, leading to uncontrolled cell growth and division in cancer
• Oncogenes are mutant forms of proto-oncogenes that accelerate cell growth and division, while tumour suppressors prevent cancer by regulating cell growth
• Tumour suppressor genes act like a brake pedal in cell proliferation, with proteins like p53 triggering apoptosis in response to excessive DNA damage
• DNA repair genes play a crucial role in preventing cancer by correcting DNA damage, with mutations in these genes leading to genetic instability and cancer development
• Cancer tends to involve multiple mutations, leading to genetic instability, metastatic disease, and uncoordinated cell growth that persists even after the initial stimuli have ceased
• Cancer is defined as an abnormal mass of tissue with uncoordinated growth that persists even after the stimuli have stopped, making the statement true
• Tumour staging involves determining the size of a tumour and how far it has spread from where it originated
• Staging is usually done via biopsy/surgery and radiology (CT/MRI/PET)
• It is important for determining treatment options and prognosis
• TNM staging system:

  • T (Tumour) refers to the size of the cancer and how far it has spread into nearby tissue, ranging from 1 (small) to 4 (large)
  • N (Node) refers to whether the cancer has spread to the lymph nodes, ranging from 0 (no lymph nodes containing cancer cells) to 3 (lots of lymph nodes containing cancer cells)
  • M (Metastases) refers to whether the cancer has spread to another part of the body, indicated by 0 (cancer hasn't spread) or 1 (cancer has spread)
• Ann Arbor Staging system used for lymphoma:

  • Stage I: single LN region
  • Stage II: >1 LN region but on the same side of the diaphragm
  • Stage III: Nodal involvement on both sides of the diaphragm
  • Stage IV: Involvement of extra-lymphatic organs
• Grading describes how abnormal cancer cells are compared to normal cells, based on their appearance under the microscope:

  • Grade 1: cancer cells look very similar to normal cells and grow slowly (low grade)
  • Grade 2: cells don't resemble normal cells and grow faster than normal (intermediate grade)
  • Grade 3: cancer cells look very abnormal and grow quickly (high grade)
• T2N3M1:

  • T2 indicates a medium-sized tumour
  • N3 suggests extensive lymph node involvement
  • M1 signifies distant metastases to another part of the body