Claims about cancer travel unusually fast, and most of them travel without a source. Rather than list them, this article answers three questions — what your actual odds are, what believing a myth costs you, and what to do instead.
1. Living to life expectancy, 44.6% of men and 38.2% of women in Korea develop cancer — about one in two men and one in three women (National Cancer Information Center, 2023).
2. Yet only 5–10% of cancers are inherited. The rest arise from changes over a lifetime.
3. The weight sits on smoking (30%), diet (30%) and chronic infection (10–25%). Where the common myths point — phones, power lines, deodorant — is not where the weight is.
Each of the three, worked through below.
What your odds are — and how much of it is inherited
Start with the Korean figures. The National Cancer Information Center reports 288,613 new cancer cases in 2023 (151,126 men, 137,487 women), up 2.5% on the year before. The cumulative probability for someone living to life expectancy:
| Group | Probability by life expectancy | In people |
|---|---|---|
| Men | 44.6% | About 1 in 2 |
| Women | 38.2% | About 1 in 3 |
| National Cancer Information Center, 2023. This is a cumulative lifetime probability, not an annual one — most of it lands in later life. | ||
At those odds, the next question is usually “what about my family?” The US National Cancer Institute treats that question as a myth in both directions.
| Question | What NCI writes | How to read it |
|---|---|---|
| Does cancer in the family make me likely to get it? | “Only about 5 to 10 percent of cancers are caused by harmful mutations that are inherited from a person's parents.” | Most cancer is not inherited |
| Does no cancer in the family make me safe? | “Most cancers are caused by genetic changes that occur throughout a person's lifetime — from aging and exposure to environmental factors.” | No family history does not remove the risk |
| The same number reassures on one side and warns on the other. That the two sit next to each other is the point. | ||
Invert “5 to 10 percent” and you get 90 to 95. What the document attributes that share to is aging and exposure to environmental factors.
What believing a myth costs
Here is the core of it. Korea's National Cancer Information Center attributes cancer deaths this way: “30% of cancer deaths are due to smoking, 30% to dietary factors, and 10–25% to chronic infection.” Occupation, heredity, alcohol, reproductive factors and hormones, radiation and environmental pollution account for roughly 1–5% each.
A myth costs you in two ways. One is spending worry on something small; the other is postponing something that matters. Collecting the NCI items that fall into the second category:
| The claim | What NCI writes | What believing it costs |
|---|---|---|
| Surgery or a biopsy spreads cancer | “The chance that surgery will cause cancer to spread to other parts of the body is extremely low.” | Diagnosis is delayed |
| Herbal products cure cancer | “No herbal product has been shown to be effective for treating cancer.” | Treatment is missed |
| Sugar makes cancer worse | “No studies have shown… that cutting sugar shrinks or eliminates cancer.” | Attention leaves the heavy items — quitting smoking, screening |
| Attitude determines the outcome | “There is no convincing scientific evidence that links a person's ‘attitude’ to their risk of developing or dying from cancer.” | It puts “you didn't fight hard enough” on the patient |
| Air exposure makes cancer worse | “Exposure to air does not make tumors grow faster or cause cancer to spread to other parts of the body.” | Surgery is put off |
| Cancer is contagious | “In general, no. Cancer is not a contagious disease that easily spreads from person to person.” | Patients are isolated |
| The right column is ours. The NCI document answers each claim without listing what believing it would cost. | ||
The “attitude” item deserves attention, because that belief builds a structure in which not recovering becomes the patient's fault. What NCI rejects is specifically the link to the risk of developing or dying from cancer — it is not a statement about quality of life or about getting through treatment.
What to do instead — Korea's ten cancer prevention rules
A list already exists that maps onto where the weight sits. Korea's National Cancer Information Center publishes it as the national cancer prevention rules, carried here as written.
| # | The rule | Which cause it addresses |
|---|---|---|
| 1 | Do not smoke, and avoid other people's smoke | Smoking, 30% |
| 2 | Eat plenty of vegetables and fruit, with a varied and balanced diet | Diet, 30% |
| 3 | Eat less salt, and avoid burnt food | |
| 4 | For cancer prevention, avoid even one or two drinks a day | Alcohol, 1–5% |
| 5 | Walk or exercise enough to sweat, 30+ minutes a day, 5+ days a week | Weight and activity |
| 6 | Maintain a healthy weight for your build | |
| 7 | Get hepatitis B and cervical cancer vaccinations per the immunisation guidelines | Chronic infection, 10–25% |
| 8 | Practise safe sex to avoid sexually transmitted infections | |
| 9 | Follow workplace safety rules to avoid exposure to carcinogens | Occupation, 1–5% |
| 10 | Attend every screening per the early detection guidelines | Not occurrence — detection |
| The rules are carried as written; pairing them with the cause shares in the right column is ours. | ||
Set against the cause shares, rules 1, 7 and 8 sit on the heavy end. Rule 10 is a different kind of item — it does not prevent cancer from arising, it finds it early when it does. Which is exactly where the “surgery spreads it” myth turns into a real cost.
One encouraging number belongs here too. NCI's first item asks whether cancer is a death sentence, and answers: “the 5-year relative survival rate for some cancers, such as breast, prostate, and thyroid, now is 90 percent or better.”
Korean cancer statistics are in cancer prevalence in Korea and thyroid cancer; the national screening programme is in this article. What families face after a diagnosis is in caring for a cancer patient.
Questions that come up
Wouldn't cutting sugar help?
What NCI writes is that no studies have shown that cutting sugar shrinks or eliminates cancer. That is not a statement that sugar is good for you — the item answers one question, whether it worsens cancer. Diet accounts for 30% of cancer deaths in the Korean figures, and it is the subject of rules 2 and 3.
Should I put off a biopsy?
The document points the other way — “the chance that surgery will cause cancer to spread to other parts of the body is extremely low.” That is “extremely low,” not zero, and whether to test is a decision with your clinician. But rule 10 says every screening, without gaps.
Is the mobile phone question settled?
Look at the shape of the sentence — “No, not according to the best studies completed to date… cell phones emit a type of low-frequency energy that does not damage genes.” The “no” carries a condition, and this article has not deleted it. The power line item has the same shape.
Does attitude really make no difference?
What NCI writes is that there is no convincing scientific evidence, and the subject is the risk of developing or dying from cancer. It is not a statement about quality of life or about getting through treatment — the document does not cover that.
Should family history mean earlier screening?
That criterion is not in this document. What NCI states is that 5 to 10 percent of cancers are inherited and that no family history does not remove the risk. Starting age and interval follow the national screening guidance and your clinician's judgement.
What we read into it
Reading the NCI document, what stands out is that the strength of the wording varies item by item.
| Wording | Which item | What it means |
|---|---|---|
| “No … has been shown” | Herbal products | The most categorical |
| “No, not according to the best studies completed to date” | Phones, power lines | A denial with a condition attached |
| “Extremely low” | Spread from surgery | Not zero |
| “Have not found evidence” | Deodorant | Not “there is none” but “we did not find it” |
| The grouping is ours; the wording is carried as written. It is also the distinction most often lost when reading agency documents. | ||
And numbers appear in only two places in that document — the family history item (5–10%) and the survival item (90% or better). Everything else is prose. Which is why Korean sources have to be placed alongside it to answer “what are my odds.”
Sources
- National Cancer Information Center, Korea (tier 1, public institution) — Cancer incidence (checked August 2026). Source for 288,613 new cases in 2023 (151,126 men, 137,487 women, up 2.5% year on year) and for the 44.6% and 38.2% lifetime probabilities for men and women.
- National Cancer Information Center, Korea (tier 1, public institution) — General cancer prevention — overview (checked August 2026). Source for “30% of cancer deaths are due to smoking, 30% to dietary factors, and 10–25% to chronic infection,” and for occupation, heredity, alcohol, reproductive factors and hormones, radiation and environmental pollution at roughly 1–5% each.
- National Cancer Information Center, Korea (tier 1, public institution) — National cancer prevention rules (checked August 2026). Source for all ten rules and their order.
- US National Cancer Institute (tier 1, government agency) — Common cancer myths and misconceptions (checked August 2026). Source for the items and their order, “the 5-year relative survival rate for some cancers, such as breast, prostate, and thyroid, now is 90 percent or better,” the answers on sugar, contagion, surgery, attitude, air exposure, phones, power lines, herbal products and deodorant, “only about 5 to 10 percent of cancers are caused by harmful mutations that are inherited from a person's parents,” and “most cancers are caused by genetic changes that occur throughout a person's lifetime — from aging and exposure to environmental factors.”
- Our own reading. The grouping by strength of wording, the observation that the two family-history items invert each other, the table pairing the prevention rules with the cause shares, and the “what believing it costs” column are ours from the source documents; none of them is presented that way in the originals.
Where to check further
- Your own screening start age and interval — the national screening programme rule 10 points to is set out on the National Cancer Information Center’s screening programme page, and summarised in the national cancer screening article.
- The research behind each item — the NCI misconceptions page states conclusions without listing individual studies. Item-level evidence lives in the fact sheets and on NCI’s pages for the specific cancer type.
- The basis of the survival figure — which period and which population “90 percent or better” refers to is not on that page. Korean figures are in a separate article.
Written as of August 2026. The Korean lifetime probabilities, cause shares and prevention rules come from the National Cancer Information Center; the myth items and their answers from the US National Cancer Institute. Grouping the wording by strength and pairing the rules with the cause shares are marked as ours. This article is general information and does not substitute for medical diagnosis or treatment. Decisions about testing and treatment belong with your clinician.
