100 years ago: Is cancer hereditary?

1. At a Glance

• What it is: an archival "100 years ago" item in The Hindu (print edition dated 9 October 2026). It reports the first findings of Dr. Louis Sambon's epidemiological expedition of 1925 into cancer. [1]
• Core claim of 1925–26: "cancer houses" and "cancer areas" do exist, even if the names may be misleading. This means cancer was being studied as a disease that clusters in particular places, not only as a family trait. [1]
• Why it matters for UPSC: it shows how thinking moved from 1920s place-based epidemiology to modern germline genetics. Inherited BRCA1/2 variants are now a measurable share of Indian breast and ovarian cancers. [1][2]
• It feeds GS-III (S&T: genetics, biotech, health tech) and GS-II (health policy, screening). It also gives Essay/GS-IV material on the "nature vs environment" debate in disease.

2. Why in the News

• Reprinted in The Hindu's archival column, International Print Edition, Page 9, on 9 October 2026, under the headline "Is cancer hereditary?". [1]
• Current hook: Indian studies of hereditary cancer genes. A 2024 European Journal of Human Genetics (Nature portfolio) study mapped the BRCA mutation spectrum among Indian breast and ovarian cancers. [2]

3. Background & Evolution

• 1925 (spring, summer, autumn): Dr. Louis Sambon led an expedition to study cancer "from the epidemiological standpoint". [1]
• c. 1926: first conclusions published in the Journal of Tropical Medicine and Hygiene. [1]
• Main finding: cancer seemed to cluster in particular houses and areas ("cancer houses", "cancer areas"). This challenged a purely hereditary or purely random explanation. [1]
• Late 20th century: cancer epidemiology became a formal discipline. The WHO's cancer agency, IARC, issued the reference text Cancer Epidemiology: Principles and Methods (1999). [3]
• 21st century: focus moved to germline (inherited) variants such as BRCA1/2. In India, recurrent "founder" mutations (e.g., BRCA1 185delAG) have been found in South Indians. [2]
• Conceptual arc: clustering by place (1920s) → environmental and lifestyle carcinogens → molecular genetics. Hereditary and environmental causes are now seen as working together, not competing.

4. Core Static Facts

Item	Fact
Researcher (1925)	Dr. Louis Sambon [1]
Study period	Spring–autumn 1925 [1]
Approach	Epidemiological (distribution of disease by place and population) [1]
Published in	Journal of Tropical Medicine and Hygiene [1]
Key concepts	"Cancer houses", "cancer areas" (the paper itself admits they may be misnomers) [1]
Modern hereditary genes	BRCA1, BRCA2 (tumour-suppressor genes; inherited variants raise breast and ovarian cancer risk) [2]
Indian BRCA data (2024)	188 patients (20.4%) carried BRCA1/2 variants: 118 (62.8%) pathogenic/likely pathogenic, 70 (37.2%) VUS [2]
Indian founder mutation	BRCA1 185delAG, recurrent in South Indians, 24.6% of pathogenic variants [2]
Global reference body	IARC, the WHO's cancer research agency [3]

Key terms:

• Germline mutation: inherited, present in every cell, passed to offspring.
• Somatic mutation: acquired during life, found only in the tumour, not inherited.
• VUS (Variant of Uncertain Significance): a variant whose link to disease is not yet clear.
• Founder mutation: a variant that is common in one population because it descends from a shared ancestor.
• Familial clustering: cases grouped in a family. It can come from shared genes or a shared environment.

5. Multi-Dimensional Analysis

Scientific / Technological

• The 1925 study used spatial epidemiology. Grouping cases by house or area pointed to environmental or local factors, not only heredity. [1]
• Modern genomics measures inherited risk directly. About a fifth of the tested Indian cohort carried BRCA1/2 variants. [2]
• About 37% of the variants found were VUS. This shows genomic reference data for Indian populations is still limited. [2]

Social

• A founder mutation concentrated in South Indians (185delAG) argues for population-specific screening panels, not imported Western panels. [2]
• Calling a cancer "hereditary" can stigmatise families, especially in marriage decisions. Genetic counselling is therefore essential.

Ethical / Governance

• Genetic test results raise issues of privacy, consent and possible insurance discrimination. These link to data-protection and bioethics debates.
• The labels "cancer houses" and "cancer areas" show how an observed correlation can be mistaken for a cause. This is a lesson in evidence-based policy. [1]

Historical

• The 1925 work belongs to the era of tropical medicine (it was published in a tropical-medicine journal). At the time, infectious and place-based explanations dominated. [1]
• The shift from place to gene shows how paradigms change in medical science.

Administrative / Health Policy

• Routine screening of the general population is costly. Cascade testing of relatives of carriers is the cost-effective option for India, consistent with the founder-mutation data. [2]

6. Recent Developments (last 12–18 months)

• 9 Oct 2026: The Hindu reprinted the 1925–26 Sambon findings in its archival column. [1]
• 2024: European Journal of Human Genetics published the Indian BRCA spectrum study. It recommended screening for BRCA1 185delAG among South Indians. [2]
• (No Tier 1 government update on hereditary-cancer policy could be retrieved within the search budget. Check PIB for the cancer-related provisions of NP-NCD and the Genome India Project.)

7. Prelims Hooks

• Dr. Louis Sambon studied cancer from the epidemiological standpoint in 1925. [1]
• His findings appeared in the Journal of Tropical Medicine and Hygiene. [1]
• He concluded that "cancer houses" and "cancer areas" definitely exist, though the names may be misnomers. [1]
• BRCA1 and BRCA2 are tumour-suppressor genes linked mainly to hereditary breast and ovarian cancer. [2]
• In a 2024 Indian cohort, 20.4% of patients carried BRCA1/2 variants. [2]
• Of these, 62.8% were pathogenic/likely pathogenic and 37.2% were VUS. [2]
• BRCA1 185delAG is a recurrent mutation among South Indians and accounts for 24.6% of the pathogenic variants found. [2]
• VUS = Variant of Uncertain Significance. It is not the same as a pathogenic variant.
• Germline mutations are inherited; somatic mutations are not passed on.
• IARC (the WHO's cancer agency) published Cancer Epidemiology: Principles and Methods in 1999. [3]

8. Where the 1925 'Cancer Houses' Idea Was Partly Right

• A cluster in a house cannot tell genes apart from surroundings
• People in one house share genes. They also share food, water, smoke and germs.
• So when cases group in one house, the cluster alone cannot show which of these is the cause [1].

• This is why Sambon himself said the labels may be misnomers (wrong names) [1].

• But some cancers really do spread through shared living

• The WHO's cancer agency, IARC, links almost 20% of cancers to long-lasting infections. Examples are hepatitis B and C viruses, HPV (human papillomavirus) and H. pylori (a stomach bacterium) [5].
• These germs pass between people who live close together. So a 'cancer house' can be real without the cause being heredity.
• Lesson for answers: do not call the 1925 work simply 'wrong'. It asked the right question with tools that could not settle it.

9. Why '20% Carry BRCA Variants' Does Not Mean 20% of Cancers Are Inherited

• The 20.4% comes from a group of patients who were tested, not from all patients
• The study counted variants among breast and ovarian cancer patients who underwent BRCA testing [2].

• Patients are usually sent for such tests when they look higher-risk, for example because of family history. A random sample of all patients would likely show a lower share.

• More than a third of the 20.4% are not proven risks

• 37.2% of the variants found were VUS (changes whose link to disease is not yet known) [2].

• Only 62.8% were pathogenic or likely pathogenic (known to cause disease) [2].

• Inherited risk is the smaller part of cancer overall

• For childhood cancer, WHO says only about 10% of children with cancer have a genetic predisposition (an inborn higher risk) [6].
• Infections alone account for almost 20% of cancers [5]. Tobacco, diet and pollution add more.
• So in a Mains answer, write 'inherited risk matters for some cancers', not 'cancer is hereditary'.

10. Should India Spend on Gene Tests When Tobacco Kills More?

• The strongest objection
• Most cancer comes from causes we can prevent — tobacco, infections, polluted water [5].
• Gene tests and counselling need trained staff and labs. In a poor health system, that money could instead buy HPV vaccines or tobacco control.

• This objection is fair. Inherited genes explain only a small share of all cancer [6].

• Why targeted testing still makes sense

• India does not need to test everyone. One South Indian founder mutation, BRCA1 185delAG, makes up 24.6% of the harmful variants found [2].
• A test for one known mutation is narrower and cheaper than reading the whole gene. The study itself recommends screening for it among South Indians [2].
• Cascade testing (testing the relatives of a person who carries the variant) aims at the families most at risk.

• A carrier found early can choose closer check-ups or preventive surgery. Prevention of tobacco use cannot help these families.

• Honest balance: prevention should get most of the money. Targeted gene testing is a small add-on for high-risk families, not a replacement.

11. What the Genome India Data Can Fix — and What It Cannot

• What it can fix: too many 'uncertain' results
• Under GenomeIndia, DBT (Department of Biotechnology) sequenced the full genomes of 10,074 healthy people from 83 population groups [4].
• The data was opened to researchers on 9 January 2025 [7].

• If a variant is common among healthy Indians, it is unlikely to cause cancer. Doctors can then move many VUS results to 'harmless'.

• What it cannot fix: rare variants in small communities

• 10,074 people across 83 groups is about 120 people per group on average [4].
• A variant carried by very few people in one community may not show up at all in such a small sample.

• The samples are from healthy people, not cancer families. It shows what is normal, but it does not directly show which variant causes cancer.

• Access rules matter

• Researchers get the data under the Biotech-PRIDE Guidelines and the FeED (Framework for Exchange of Data) protocols [4].
• These control who uses genetic data and how. This links to the privacy questions under the DPDP Act, 2023.

12. Who Should Act Next

• ICMR and DBT: build an Indian list of cancer variants
• Match variants from Indian cancer patients [2] against the GenomeIndia data of healthy Indians [4].

• This gives Indian labs a shared, Indian reference instead of relying only on Western data — and cuts VUS reports.

• Health Ministry, under NP-NCD: add family-risk questions to existing cancer screening

• NP-NCD (the national programme for non-communicable diseases) already screens for common cancers.

• Asking about cancer in close relatives at that visit can pick out families to send for cascade testing.

• States in the South: offer the BRCA1 185delAG test first

• The founder mutation is concentrated among South Indians, as the 2024 study recommends [2].

• Keep prevention as the main tool

• Infection-linked cancers (HPV, hepatitis) can be prevented by vaccines and treatment [5]. These reach far more people than gene testing can.

13. Anchors for Answers

• Data: BRCA1/2 variants in 20.4% of tested Indian breast/ovarian cancer patients; 37.2% of these were VUS [2]
• Data: Almost 20% of cancers linked to chronic infections (hepatitis viruses, HPV, H. pylori) [5]
• Data: GenomeIndia — whole genomes of 10,074 healthy Indians from 83 populations, opened to researchers on 9 Jan 2025 [4][7]
• Report/Committee: IARC, Cancer Epidemiology: Principles and Methods (1999) [3]
• Law/Case: Digital Personal Data Protection Act, 2023 (privacy of genetic and health data); Biotech-PRIDE Guidelines for genomic data sharing [4]
• Scheme: GenomeIndia (DBT) — Indian reference genomes to cut VUS results; NP-NCD — base for adding family-history screening

14. Mains Relevance

• GS-III: Science & Technology, covering developments and their applications in everyday life, biotechnology, and genomics.
• GS-II: Issues relating to the development and management of Health services.
• GS-IV / Essay: ethics of genetic information, and "correlation vs causation" in public reasoning.
• Question stems: 1. Cancer is increasingly seen as an interplay of inherited susceptibility and environmental exposure. Discuss with reference to India's cancer-screening strategy. (GS-III, 15 marks) 2. Population-specific genomic data is essential for precision medicine in India. Examine in the light of founder mutations and the Genome India initiative. (GS-III, 10 marks) 3. Discuss the ethical issues in predictive genetic testing for hereditary diseases. (GS-IV, 10 marks)

15. Related Topics to Study Next

• Genome India Project (DBT): population-specific reference genomes, which help cut down VUS results.
• National Programme for Prevention & Control of NCDs (NP-NCD): India's framework for screening for common cancers.
• National Cancer Registry Programme (ICMR-NCDIR): source of incidence data and regional cancer "hotspots", a modern version of "cancer areas".
• IARC carcinogen classification (Groups 1–4): the environmental side of cancer causation.
• CRISPR / gene therapy and CAR-T (e.g., India's indigenous CAR-T): applied genetics in cancer treatment.
• Digital Personal Data Protection Act, 2023: privacy of genetic and health data.
• Arsenic and uranium in groundwater; Punjab's "cancer belt": current examples of place-linked cancer clustering.

16. NCERT Concepts to Revise

• Correlation vs causation (Economy): The 1925 'cancer houses' idea shows how clustering in places can be mistaken for a cause.
• Digital Personal Data Protection Act 2023 (Polity): Genetic test results are sensitive health data, raising privacy and consent questions this law addresses.
• Screening (Economy): Cascade testing and BRCA screening of at-risk groups are central to India's cancer-control strategy.
• Groundwater (Geography): Arsenic and uranium in groundwater are environmental causes behind place-linked cancer clusters like Punjab's cancer belt.
• Uranium (Geography): Uranium contamination is a named example of an environmental exposure that can cluster cancer in an area.

17. Common Errors / Trap Areas

• Familial ≠ hereditary: a cluster in one house or family can come from a shared environment, as the 1925 "cancer houses" idea shows, not only from shared genes. [1]
• Germline vs somatic confusion: most cancer mutations are somatic and are not inherited.
• VUS is not pathogenic: do not count VUS carriers as "high-risk" in statistics. [2]
• BRCA is not only about women: BRCA variants also affect men, e.g., male breast and prostate cancers. Do not restrict BRCA to women.
• Journal attribution: Sambon published in the Journal of Tropical Medicine and Hygiene, not The Lancet or Nature. [1]