Understanding Cancer Risks Flashcards
Calculate and interpret relative risk
Relative risk= absolute risk of group w/ factor / absolute risk of group w/o factor
** Pay attention to what question is asking to determine numerator and denominator**
How to evaluate risk factors
Risk factors may be correlative rather than causative ; look at strength of evidence (how well was study done, multiple studies?, dose dependent, is there plausible biological reason to explain how risk factor affects risk of dx), size of associated relative risk (ideal 95% confidence interval; association may just not be strong), and impact of risk factor
major risk factors for mammary cancer
- unspayed or spayed late more likely to get mammary cancer
- spay before 1st heat= preventative
- spay before 2nd or 3rd heat= somewhat preventative
- after 3rd heat not very preventative
major risk factors for lymphoma
- BLV in cattle accounts for 85-90% lymphoma cases in adult cattle
- FeLV
- FIV
- environmental exposure to smoke
- neutered males higher risk lymphoma than unfettered males (Golden retriever study)
major risk factors for skin cancer
- sun exposure
- white/ light colored animals
- older white/ grey horses
- white cats
- herrford cattle
major risk factors for bone cancer
- Large breed dogs
Describe limitations of risk factor studies
- results only applicable to similar groups of individuals (if look at results regarding 10YO dogs have to do different study for 8YO ect.)
- Values result from comparison of highest and lowest exposure groups; most individuals exposures are between extremes
- findings apply to groups not individuals
General recommendations for avoiding cancer in pets
- Routine veterinary evaluations
- Maintain healthy lifestyle in your pet (spay/ neut/ exercise)
- Feed healthy well balanced diet (veggies decrease bladder cancer risk)
retrospective study
these are case-control studies, determine odds ratios;
retrospective- look at group who have dx and group who don’t and see factors of those who have dx and those who don’t
relative risk 2.4 for lymphoma of cigaret smoke exposed cats tells you
the absolute risk of lymphoma in cats who are exposed to cigaret smoke is 2.4 x greaser than the absolute risk of lymphoma in cats not exposed to cigaret smoke
Relative risk tells you how two groups relate not absolute value
relative risk 2.4 for lymphoma of cigaret smoke exposed cats tells you
the absolute risk of lymphoma in cats who are exposed to cigaret smoke is 2.4 x greaser than the absolute risk of lymphoma in cats not exposed to cigaret smoke
Relative risk tells you how two groups relate not absolute value
impact of a risk factor
depends on size of relative risk and how many individuals have that risk factor
Women with breast cancer have BRCA-1 mutation
RR= 5
mutation not v common so only in 2-4% of cases but if you have mutation chance of getting dx v high so impact on population is low though RR is high
Obesity and breast cancer
obesity RR= 2 but obesity in 1/3 population so in 30-50% breast cancer bc common in population so lower risk factor but more people affected
risk factors applicable to groups or individuals
GROUPS ONLY
ways to use risk factor studies
- screening tools (place individuals in high risk groups for monitoring if v strong association with dx can provide worthwhile screen
- ID risk reductions strategies
- Stepping stones for future studies to validate and ID causal mechanisms
General cancer risk factors for vet patients
- Age
- Physical featrues
- Hormonal
- Envionrmental
- Hereditary factors (breed predisposition)
Common sense screening for pets
- only risk factors with very strong associate w/ dx can provide worthwhile screen
General recoomendations - routine oral exams
- routine rectal exams
- evaluation of skin/ soft tissue masses (check in between toes and the ear canals too)
- know how to check for mammary masses, enlarged lymph nodes
- observe changes in appetite and bathroom habits
Common sense screening for pets
- only risk factors with very strong associate w/ dx can provide worthwhile screen
General recoomendations - routine oral exams
- routine rectal exams
- evaluation of skin/ soft tissue masses (check in between toes and the ear canals too)
- know how to check for mammary masses, enlarged lymph nodes
- observe changes in appetite and bathroom habits
- when animal gets older and risk factors are then higher might be worth spending more on further diagnostic tests to try to catch things earlier
- Regular PEs with older pets
-Lab tests (though bloods normal in a lot of cancer) - Imaging (Rads coughing/ lameness), abdominal U/S signs concern for splenic of bladder cancer
Common sense screening for pets
- only risk factors with very strong associate w/ dx can provide worthwhile screen
General recoomendations - routine oral exams
- routine rectal exams
- evaluation of skin/ soft tissue masses (check in between toes and the ear canals too)
- know how to check for mammary masses, enlarged lymph nodes
- observe changes in appetite and bathroom habits
- when animal gets older and risk factors are then higher might be worth spending more on further diagnostic tests to try to catch things earlier
- Regular PEs with older pets (1-2x per year) (mammary glands, oral cavity, skin, LNs, perineum)
-Lab tests (though bloods normal in a lot of cancer) (cbc/ chem/ u/a) - Imaging (Rads coughing/ lameness), abdominal U/S signs concern for splenic of bladder cancer
- know what cancers are common and be vigilant
- remember that risk increase with age but never rule it out as a differential
Relative risk >1
increased risk
Relative risk <1
decreased risk
cancer risk
the chance or probability that cancer will occur
risk factor
characteristic associated with cancer prevalence
absolute risk
chance of getting cancer for a group of individuals; represents the group risk oot the risk of any individual in the group
relative risk
relationship of characteristic factor to cancer risk; ration of absolute risk of group w/ factor and absolute risk of group w/o factor
how do we determine if characteristic is a risk factor
determine the relative risk
prospective study
looks forward (do cohort study where we have group of interest exposed to risk factor and we monitor for dx and then we look at group not exposed to risk factor and monitor for dx)
how can risk factor be evaluated
strength of evidence, size of associated relative risk, and impact of risk factor
