Which statement describes a benign tumour?

• It does not invade nearby tissue or spread to distant sites.
• It has not spread to distant sites, although it invades nearby tissue.
• It is too small to cause symptoms, although its cells invade nearby tissue.

Which statement defines a risk factor for a disease?

• A feature known to cause the disease through a demonstrated biological pathway.
• A feature linked to a higher chance of developing the disease.
• A feature used to identify the disease once symptoms have already appeared.

If a virus increases a person's cancer risk, the resulting cancer must also be passed from person to person.

A study finds more disease among people with a measured feature. No further causal evidence is supplied. Which conclusion is supported?

• The feature contributes to causing disease by changing how cells function.
• The feature is associated with disease; the cause of the link is unresolved.
• The disease changes the feature, explaining why they occur together.

Which statement describes a mechanism linking tobacco smoke to cancer?

• People exposed to tobacco smoke have more lung cancer than people without that exposure.
• Lung cancer rates fall in populations where smoking becomes less common over time.
• Smoke chemicals damage DNA and can disrupt the controls on cell division.

Which process produces new abnormal cells as a tumour grows?

• Abnormal cells keep dividing after their division controls break down.
• Existing abnormal cells enlarge as they absorb nutrients from the blood.
• Existing abnormal cells move into spaces between nearby healthy cells.

A tumour presses on an organ and has invaded nearby tissue. Tests find no distant spread. Which classification and reason fit?

• A benign tumour, because pressure on an organ results from growth in one place.
• A malignant tumour, because invasion of nearby tissue is malignant behaviour.
• A benign tumour, because tests have not detected spread to a distant part of the body.

A student says, 'Someone stopped smoking and later developed lung cancer, so stopping smoking cannot lower risk.' Which reply addresses the error?

• The later diagnosis shows that inherited factors caused this person's cancer.
• The later diagnosis shows that smoking was only a risk marker in this person's case.
• A lower chance of lung cancer still allows some people who stop to develop it.