Inquiry Question 3: Why are epidemiological studies used?
Investigate the treatment, management and possible future directions for the cure of non-infectious diseases using an example that has been treated by both pharmaceutical and medical interventions, including education programs and screening
A focused HSC Biology Module 8 answer on preventing non-infectious disease: education campaigns (SunSmart, QUIT), population screening (BreastScreen, bowel, cervical) and genetic engineering approaches (carrier and preimplantation genetic screening, gene therapy) that prevent inherited disease.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
NESA wants you to describe how non-infectious disease can be prevented or its burden reduced through education, screening and other interventions, using named Australian examples. The strategies fall into three broad families: education campaigns (changing behaviour), screening programs (catching disease, or those at risk, early) and genetic engineering (acting directly on the genetic cause of inherited disease through carrier screening, preimplantation genetic diagnosis and gene therapy).
The command words matter. "Outline" and "describe" want the strategy and how it works; "explain" wants the cause-and-effect link to a fall in incidence or mortality; "evaluate" wants a justified judgement weighing strengths and limitations. Marks are won by linking each strategy to how it reduces the disease burden, not by merely naming the campaign.
The answer
Prevention of non-infectious disease operates at three levels:
- Primary prevention. Stops disease occurring (vaccination, smoking cessation, sun protection, embryo selection).
- Secondary prevention. Detects disease, or those at risk, early (screening).
- Tertiary prevention. Reduces complications of established disease (rehabilitation, ongoing management).
The three prevention strategies below cut across these levels: education and structural regulation are mostly primary, screening is mostly secondary, and genetic engineering can act before conception (PGD), before pregnancy (carrier screening) or on an affected patient (gene therapy).
Education programmes
Education increases health literacy and changes behaviour. Effective programmes have clear messaging, repeated exposure, structural support (regulation, infrastructure) and target specific behaviours.
- SunSmart
- Launched 1981 by Cancer Council Victoria with the Slip-Slop-Slap slogan; expanded to Slip-Slop-Slap-Seek-Slide. Targets skin cancer through sun protection. Backed by no-hat-no-play policies in schools, shade structures, and free sunscreen.
- QUIT
- Tobacco cessation campaign with graphic warnings, plain packaging (2012), the Quitline, nicotine replacement subsidies on the PBS, and indoor smoking bans. Adult smoking rates fell from 35 percent in 1980 to under 11 percent in 2022.
- LiveLighter
- Targets obesity, diabetes and cardiovascular disease through advertising on the harms of excess sugar and processed food. More mixed evidence on outcomes; obesity rates have continued to rise, suggesting education alone is insufficient.
- Drink Wise / Don't Drink and Drive
- Targets alcohol-related disease and trauma through warning labels, advertising restrictions and graphic campaigns.
Screening programmes
Screening tests asymptomatic people to detect disease early, when treatment is more effective and survival is higher.
Criteria for effective screening (Wilson and Jungner).
- The disease is important and detectable in a preclinical phase.
- The test is sensitive, specific, affordable and acceptable.
- Effective treatment exists for early-stage disease.
- Screening is cost-effective.
- BreastScreen Australia
- Free biennial mammography for women aged 50 to 74. Detects ductal carcinoma in situ and small invasive cancers before they are palpable. Reduces breast cancer mortality by approximately 20 to 25 percent in regularly screened women.
- National Cervical Screening Programme
- Since 2017, replaced two-yearly Pap smears with five-yearly HPV testing from age 25. Combined with the HPV vaccine (introduced 2007), cervical cancer incidence has halved and Australia is on track to be the first country to effectively eliminate cervical cancer.
- National Bowel Cancer Screening Programme
- Free immunochemical faecal occult blood test (iFOBT) every two years for adults aged 50 to 74, mailed directly to homes. Detects adenomatous polyps and early bowel cancer. Has reduced bowel cancer mortality by approximately 15 to 20 percent in screened groups.
- Newborn screening (heel prick test)
- Within 48 hours of birth, blood is tested for over 25 conditions including phenylketonuria, congenital hypothyroidism and cystic fibrosis. Early detection allows dietary or hormonal intervention that prevents severe disability.
- Mole-watch and skin checks
- Not a formal national programme, but Cancer Council and GP-led skin checks identify melanoma early. Self-examination using the ABCDE rule (Asymmetry, Border, Colour, Diameter, Evolution) is taught widely.
Genetic engineering: preventing inherited disease at its source
Education and screening are powerful for lifestyle and environmental disease, but they cannot remove an inherited mutation - you cannot behave your way out of a faulty allele, and a screening test only detects it. For inherited (genetic) disease, a third family of strategies acts directly on the genetic cause. This is the part of the dot point students most often leave thin, yet "future directions for the cure" of disease is exactly where NESA expects genetic engineering.
- Genetic carrier screening (before pregnancy)
- Prospective parents' DNA is tested for recessive disease alleles - commonly cystic fibrosis, spinal muscular atrophy and fragile X (Medicare-subsidised in Australia since 2023). If both partners carry the same recessive allele, each child has a chance of being affected, and the couple can make informed reproductive choices.
- Preimplantation genetic diagnosis (PGD)
- During IVF, a few cells are biopsied from each early embryo and tested for the known disease allele. Only unaffected embryos are implanted, so a child who would have inherited the disorder is never conceived. PGD is used for serious single-gene disorders such as cystic fibrosis, Huntington's disease and beta-thalassaemia.
- Prenatal screening
- Combined first-trimester screening and non-invasive prenatal testing (NIPT) - which sequences fragments of fetal DNA in the mother's blood - detect chromosomal conditions such as trisomy 21 during pregnancy.
- Gene therapy
- Rather than selecting embryos, gene therapy corrects the genome of an affected patient, usually by delivering a functional copy of the faulty gene inside a modified, harmless viral vector. Zolgensma delivers a working SMN1 gene to infants with spinal muscular atrophy; Luxturna treats an inherited form of blindness; gene-editing trials (CRISPR) are now curing some patients of sickle-cell disease and beta-thalassaemia. Gene therapy is the clearest "future direction for the cure" of single-gene disease.
The key contrast: carrier screening and PGD prevent the allele being passed on (reproductive prevention), whereas gene therapy corrects the fault in a living patient (a cure). Both differ fundamentally from education and screening, which act on behaviour and detection, not on the gene itself.
Structural and regulatory interventions
Education is more effective when backed by structural change.
- Tobacco. Plain packaging (2012), high pack price (now over $50), indoor and outdoor smoking bans, graphic warnings.
- Alcohol. Minimum unit pricing, advertising restrictions, drink-driving limits.
- Diet. Health Star Rating system, kilojoule labelling on menus, sugar tax debates.
- Sun safety. UV Index broadcasting, shade structures, school sun-protection policies.
- Genetic. Newborn screening mandate, subsidised carrier screening through Medicare.
How a prevention program changes disease incidence over time
The success of a prevention strategy is judged from epidemiological data: does the incidence (new cases) of the disease fall after the program begins? The figure below shows the characteristic pattern for cervical cancer in Australia - a fall after the 1991 screening program, sustained by HPV vaccination, towards the elimination threshold.
Reading the graph in an exam: state the trend (incidence falls from about 14 to under 7 per 100 000), tie it to the intervention dates (1991 screening, 2007 vaccination), but stay cautious about causation - incidence was already drifting down before 1991, and the vaccine's full effect appears only as vaccinated cohorts age. This caution is exactly what the 2022 HSC marking guidelines rewarded.
Examples in context
- Example 1. National Bowel Cancer Screening Program in Australia
- Since 2006, the Australian Government has mailed free faecal immunochemical test (FIT) kits to every Australian aged 50 to 74 every two years. Participants collect a small stool sample and post it to a pathology lab, where the test detects haemoglobin from microscopic bleeding from polyps or early bowel cancer. Positive samples trigger referral for colonoscopy, where polyps are removed before they become malignant. Bowel Cancer Australia reports that participants in the program have a 40 percent lower mortality from bowel cancer than non-participants. With about 50 percent uptake, the program prevents an estimated 90 000 deaths over 40 years, making it among the most cost-effective Australian preventive health interventions.
- Example 2. Plain packaging laws and Australian smoking rates
- From December 2012, Australia became the first country to mandate plain-packaging of cigarettes: drab dark-brown packs with large graphic health warnings replaced branded packaging. Combined with steep excise increases (a pack of 25 cigarettes now exceeds 50 AUD), the policy has driven smoking prevalence from 16.1 percent of adults in 2011-12 to 8.3 percent in 2022, according to ABS National Health Survey data. Lung cancer incidence has begun to fall about 20 years behind the smoking peak, reflecting the long lag time between exposure cessation and cancer reduction. The policy is now imitated in over 20 countries, demonstrating how structural regulation can outperform individual behavioural counselling for population-scale change.
- Example 3. Genetic engineering against spinal muscular atrophy (SMA)
- SMA is an inherited, recessive single-gene disorder caused by a faulty SMN1 gene; the severe form once killed most affected infants by age two. Australia now attacks it on three genetic fronts. Carrier screening (Medicare-subsidised since 2023) tells prospective parents if they both carry the recessive allele. Couples at risk can use preimplantation genetic diagnosis to implant only unaffected IVF embryos. And for affected babies, the gene therapy Zolgensma delivers a working copy of SMN1 inside a harmless viral vector in a single infusion, restoring motor-neuron function. Together these show how genetic engineering can prevent or cure a disease that education and screening alone could never remove, because the cause is written into the genome.
Exam-style practice questions
Practice questions written in the style of NESA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2022 HSC6 marks[A graph shows the incidence of cervical cancer in Australia from 1985β2015; over this period a national screening program (from 1991) and an HPV vaccination program were introduced.] Evaluate the success of these campaigns in reducing the incidence of cervical cancer in Australian women. Include reference to the data in your answer.Show worked answer β
An evaluate question β top marks give a well-informed judgement based on detailed analysis of the stimulus.
- Screening program
- the drop in incidence to about half after the 1991 screening program suggests it was effective. But caution: you cannot conclude causation from the numbers alone β other factors may have changed, and incidence was already falling before 1991, so the decline may have continued anyway.
- HPV vaccination program
- because HPV causes most cervical cancers, vaccinating (ideally the whole population, including boys) should reduce viral load and add to prevention. However, the data show no clear reduction in incidence since vaccination began β likely because screening was already very effective, and because vaccinated school-aged students will only show reduced cancer years later in older age groups.
- Judgement
- public health programs appear effective for prevention, but they must run for many years and be studied separately before each campaign's true effect can be properly assessed.
Source: NESA 2022 HSC Biology examination and marking guidelines.
2025 HSC3 marks[A graph shows the UV level across a single day. The Cancer Council suggests sun protection whenever the UV level is 3 or above; a sunscreen product's information suggests using sunscreen between 10 am and 4 pm.] Using the graph, evaluate the information provided on the sunscreen product with regard to the Cancer Council suggestion.Show worked answer β
Top marks need an accurate evaluation of the product statement showing a sound understanding of the graph data.
Judgement: the product statement (10 amβ4 pm) is incorrect / inadequate because a person would not be fully protected from UV.
Use the data: the graph shows UV is 3 or above between approximately 8 am and 6 pm. So following the Cancer Council's threshold, protection is needed for roughly 2 hours before and 2 hours after the product's recommended window β during which the product's advice would leave a person unprotected. Markers reward explicitly relating both the Cancer Council suggestion and the product info to the graphed UV values to give an evidence-based judgement.
Source: NESA 2025 HSC Biology examination and marking guidelines.
2024 HSC3 marksExplain how an educational program or campaign can be used to decrease the incidence of a disease caused by environmental exposure. (Name the disease.)Show worked answer β
Three marks need to explain how the program decreases incidence (cause and effect), not just list its features.
Sample (disease: skin cancer): An educational program in schools could teach students that UV exposure causes skin cancer and that, to protect themselves, they should wear hats and sunscreen when outside. This increases understanding of the risk, which increases compliance with protective behaviour, thereby preventing the cause of skin cancer (UV rays damaging DNA in cells) and so decreasing its incidence.
Marker note: the key to the top band is linking the program's features to a decrease in incidence via changed behaviour β students who only describe a campaign without that causal link score lower.
Source: NESA 2024 HSC Biology examination and marking guidelines.
Practice questions
Original practice questions graded from foundation to exam level, each with a full worked solution. Try them before revealing the solution.
foundation2 marksDistinguish between primary and secondary prevention of non-infectious disease, giving one Australian example of each.Show worked solution β
1 mark - primary prevention. Primary prevention stops a disease occurring by removing or reducing the cause before any disease is present - for example the SunSmart campaign reducing UV exposure to prevent skin cancer (or HPV vaccination, or smoking cessation).
1 mark - secondary prevention. Secondary prevention detects disease early, in a preclinical or asymptomatic phase, so treatment is more effective - for example BreastScreen Australia mammography (or the National Bowel Cancer Screening Program).
The contrast must be explicit: primary acts before disease occurs, secondary acts to find it early. A correct named Australian example is required for each mark.
foundation3 marksOutline the role of each of the following in preventing inherited disease: (a) genetic carrier screening, (b) preimplantation genetic diagnosis (PGD), (c) genetic counselling.Show worked solution β
- 1 mark - carrier screening
- Carrier screening tests prospective parents' DNA for recessive disease alleles (for example cystic fibrosis, spinal muscular atrophy) so couples learn whether they are carriers before a pregnancy.
- 1 mark - PGD
- Preimplantation genetic diagnosis tests embryos created by IVF for the disease allele and selects only unaffected embryos for implantation, so an affected child is not conceived.
- 1 mark - genetic counselling
- Genetic counselling interprets the results and recurrence risk, helping the couple make informed reproductive decisions.
Each part must be tied to its specific job (test parents / test and select embryos / advise on risk). Naming a technique without its preventive function does not earn the mark.
foundation2 marksExplain why a screening test detects disease but does not, by itself, prevent that disease from occurring.Show worked solution β
1 mark - what screening does. A screening test examines asymptomatic people to detect disease (or a precursor) early, when treatment is more effective and survival is higher.
1 mark - why it is not prevention of occurrence. Detection happens after the disease (or change) has already begun, so screening lowers mortality, not incidence - except where it removes a premalignant lesion (e.g. a colonic polyp or high-grade cervical lesion), which does prevent the cancer that would have followed.
Full marks need the distinction between detecting early (reduces death) and preventing onset (reduces incidence), plus the premalignant-lesion exception.
core4 marksGenetic engineering is increasingly used to prevent inherited disease. Describe how gene therapy and preimplantation genetic diagnosis (PGD) each work, and explain how each prevents disease in different ways.Show worked solution β
Award up to 4 marks for a correct description of both technologies plus a clear contrast of how each prevents disease.
Gene therapy (2 marks). Gene therapy introduces a functional copy of a gene into a patient's cells (often using a modified viral vector) to correct or compensate for a faulty allele. For example, in spinal muscular atrophy the therapy Zolgensma delivers a working SMN1 gene. This prevents disease by fixing the molecular cause within the affected individual - it is corrective rather than reproductive.
PGD (2 marks). PGD tests IVF embryos for a known disease allele and implants only unaffected embryos, so a child who would have inherited the disorder is never conceived. This prevents disease at the reproductive / population level by stopping the allele being passed on, rather than treating an existing person.
The discriminator: gene therapy corrects the genome of a living patient; PGD selects against affected embryos so the disease never arises. An answer describing only one, or blurring the two mechanisms, caps below full marks.
core5 marksUsing cervical cancer in Australia as an example, describe how primary, secondary and tertiary prevention strategies have combined to reduce the burden of a non-infectious disease.Show worked solution β
- 1 mark - primary prevention
- HPV vaccination of 12 to 13 year olds (girls from 2007, boys from 2013), free through schools, reduces infection with the HPV strains that cause most cervical cancer - stopping the cause.
- 1 mark - secondary prevention
- Five-yearly HPV-DNA screening from age 25 (since 2017, replacing two-yearly Pap smears) detects infection and precancerous change early, when it is easily treated.
- 1 mark - tertiary prevention
- Colposcopy and treatment of high-grade lesions removes premalignant tissue and manages established disease, preventing progression and complications.
- 1 mark - integration
- The three levels reinforce each other: vaccination lowers infection, screening catches what slips through, treatment removes lesions - together cutting both incidence and mortality.
- 1 mark - outcome / data
- Cervical cancer incidence has fallen from about 14 per 100 000 (1991) to under 7 per 100 000 (2022), and Australia is projected to effectively eliminate the disease (under 4 per 100 000) by around 2035.
Band 6 answers name a strategy at each level AND link them to the measured fall in incidence.
core4 marksExplain why an education campaign is often more effective at preventing disease when it is combined with structural or regulatory change. Use one named Australian example.Show worked solution β
- 1 mark - what education does
- Education (e.g. QUIT) raises health literacy and awareness of a risk (smoking causes lung cancer and cardiovascular disease), which can change individual behaviour.
- 1 mark - the limitation
- Awareness alone often fails to change entrenched behaviour in everyone, because of addiction, habit, cost pressures and unequal access to information.
- 1 mark - structural support
- Regulation removes the choice or raises the cost of the harmful behaviour: plain packaging (2012), high excise (a pack now exceeds $50), indoor and outdoor smoking bans, graphic warnings.
- 1 mark - combined effect / evidence
- Together they drove adult smoking from about 16 percent (2011-12) to 8.3 percent (2022) - a fall larger than education or regulation alone would achieve.
Full marks need the causal logic (education informs, regulation enforces) tied to the named example and an outcome figure.
exam7 marksGenetic engineering, education programs and screening campaigns are all used to prevent non-infectious disease. Evaluate the use of genetic engineering (such as gene therapy, carrier screening and preimplantation genetic diagnosis) as a strategy for preventing inherited disease, compared with population education and screening campaigns.Show worked solution β
"Evaluate" requires a judgement that weighs strengths and limitations against the purpose - preventing inherited (genetic) disease. A Band 6 response reaches a reasoned conclusion, not just a description.
- What genetic engineering offers (2-3 marks)
- Genetic approaches act on the actual genetic cause. Carrier screening identifies couples at risk before pregnancy; PGD selects unaffected IVF embryos so an affected child is never conceived; gene therapy (e.g. Zolgensma for spinal muscular atrophy) inserts a functional gene to correct the disorder in an affected person. For a single-gene inherited disease these are highly targeted and can prevent the disease entirely in that family or individual - something education and population screening cannot do, because you cannot "behave" your way out of an inherited mutation.
- Strengths and limitations weighed (2-3 marks)
- Genetic engineering is expensive, technically demanding and ethically contested (embryo selection, eugenics concerns, consent, equity of access), and gene therapy currently works for only a few conditions. Education and screening are cheap, scalable and population-wide and excel at lifestyle and environmentally caused disease (skin cancer, smoking-related cancer, bowel cancer), but they cannot prevent a purely inherited mutation - screening only detects carriers or affected fetuses, and education cannot remove an inherited allele. Education/screening also reach far more people per dollar and raise fewer ethical concerns.
- Judgement (1-2 marks)
- A supported conclusion: for inherited single-gene disease, genetic engineering (carrier screening plus PGD, with gene therapy where available) is the most directly effective preventive strategy, because it addresses the genetic cause that education and screening cannot remove - but it is costly, limited in scope and ethically sensitive, so it complements rather than replaces the cheaper, population-scale education and screening campaigns that prevent the far larger burden of lifestyle and environmental disease. An answer that lists features without an explicit, justified judgement caps below full marks.
exam6 marksA public-health authority introduces a national screening program for a non-infectious disease. Discuss the criteria that should be met for such a program to be effective, and analyse why a program can fail to reduce mortality even when the test itself is accurate.Show worked solution β
Target a sequenced response that applies the screening criteria, then analyses real failure modes.
Criteria for effective screening (2-3 marks). Using the Wilson and Jungner framework: the disease must be important and have a detectable preclinical phase; the test must be sensitive, specific, affordable and acceptable; an effective treatment must exist for early-stage disease; and the program must be cost-effective. If early detection does not change the outcome, screening adds no benefit.
Why an accurate test can still fail (2-3 marks). Even with an accurate test, mortality may not fall because of low uptake / participation (people do not attend), inequity (Indigenous, remote and lower-income groups participate less, so benefit is uneven), false positives causing harm and overdiagnosis (treating cancers that would never have caused harm), and lack of follow-up (a positive result with no accessible treatment changes nothing). Screening only works as a system: test plus participation plus follow-up plus treatment.
Full marks need the criteria applied (not just listed) AND at least two valid system-level reasons a program can fail despite an accurate test.
