Cancer Disparities
What is a cancer health disparity?
A difference in cancer burden or outcomes experienced disproportionately by certain population groups.
What are the six major stages of the cancer continuum, in order?
Answer:
Etiology → Prevention → Detection → Diagnosis → Treatment → Survivorship.
What is a mutation?
A permanent change in the DNA sequence.
What is the basic difference between an oncogene and a tumor suppressor gene?
Oncogenes promote excessive growth/division when activated or altered, while tumor suppressor genes normally restrain division or promote processes such as apoptosis.
What is metastasis, and why is it so clinically important?
The spread of cancer to distant organs; it is a major cause of cancer morbidity and mortality.
Name four ways a cancer disparity can be measured.
What is the difference between cancer screening and cancer diagnosis?
Screening looks for cancer before symptoms appear; diagnosis determines whether a disease is actually present.
What is the central dogma of molecular biology?
DNA → RNA → Protein.
Why are proto-oncogenes often compared to a green light and tumor suppressor genes to a red light?
Proto-oncogenes normally promote division when appropriate, while tumor suppressors tell cells to slow or stop division.
What do T, N, and M represent in cancer staging?
Tumor, lymph nodes, and metastasis.
Cancer incidence and mortality are decreasing overall, but one population is improving much more slowly than others. Can this still be considered a cancer disparity? Why?
Yes. A disparity can exist even when outcomes improve overall if the improvement is not experienced equally across population groups.
Why can a disparity in cancer screening eventually contribute to a disparity in mortality?
Reduced screening can delay detection, potentially leading to later diagnosis and affecting treatment options and outcomes.
How can a change in DNA ultimately change the behavior of a cell?
A DNA change can alter the resulting RNA and protein, potentially changing the protein's function and therefore the cell's behavior.
What are three possible responses p53 can trigger when a cell is under stress or damaged?
Cell-cycle arrest, senescence, and apoptosis.
Can a tumor develop if cell division increases but apoptosis remains normal? Explain.
Yes. Increased proliferation alone can disrupt normal tissue homeostasis and contribute to tumor formation.
Two populations have the same cancer incidence, but Population A has much higher mortality. What does this tell you—and what does it NOT tell you?
It tells you there is a disparity in cancer mortality/outcomes. It does not tell you what is causing it. Differences could arise at diagnosis, treatment, survivorship, or from interacting social, environmental, healthcare, structural, and biological factors.
A community has good access to screening, but patients with abnormal results frequently fail to receive diagnostic follow-up. Where is the problem occurring in the continuum?
Between detection/screening and diagnosis.
What is one major difference between how normal cells and cancer cells respond to signals controlling cell division?
Normal cells have regulated signaling and responses; cancer cells have dysregulated signaling and may continue dividing when they should stop.
How could a single nucleotide change in TP53 affect p53 function?
A point mutation can change a codon and therefore an amino acid—a missense mutation—which can alter the structure/function of p53.
Why does HPV-18 cause p53 to become nonfunctional in HeLa cells?
HPV-18 produces the E6 oncoprotein, which causes p53 degradation.
Black patients and patients with Medicaid are less likely to complete a follow-up colonoscopy after an abnormal stool-based test. Explain how this example demonstrates that cancer disparities can develop across the cancer continuum.
The disparity is not necessarily in whether cancer initially develops. A difference in access to or completion of follow-up after screening can affect diagnosis and potentially later treatment and outcomes. It demonstrates how inequities at one point in the continuum can contribute to downstream disparities.
Why might eliminating a disparity at one point in the cancer continuum fail to eliminate the overall cancer disparity?
Because disparities can occur at multiple stages. Equal screening, for example, does not guarantee equal diagnosis, treatment, adherence, survivorship, or outcomes.
Why does cancer risk generally increase with age?
Mutations accumulate over time, increasing the opportunity for multiple mutations involved in tumorigenesis to develop.
Explain how a TP53 mutation can ultimately lead to loss of cell-cycle arrest.
P53 mutation → altered p53 protein → impaired p53 function → failure to properly respond to DNA damage → loss of cell-cycle arrest → damaged cells can continue dividing.
Why is cancer so difficult to target and treat?
Cancer develops through multistage tumorigenesis involving the accumulation of multiple mutations, creating biologically complex tumors rather than a disease caused by one universal defect.