Cancer Education Series
Cancer Prevention and Early Detection
At least 40% of all cancers are preventable through lifestyle choices, vaccination, and environmental awareness. For those that are not preventable, early detection changes outcomes. This guide covers what the evidence actually shows about reducing your risk and catching cancer early.
250 Years of Cancer Discovery
The story of cancer medicine is a story of slow, hard-won progress. From the first observation that environmental exposures cause cancer to the development of vaccines that prevent it and immunotherapies that unleash the immune system against it, each milestone built on decades of work. Here are the discoveries that changed the field.
First Occupational Cancer Identified
Percivall Pott linked chimney soot to scrotal cancer in chimney sweeps. This was the first documented evidence that external exposures can cause cancer, a breakthrough that took centuries to fully appreciate.
The Pap Smear Is Developed
George Papanicolaou developed the Pap smear for cervical cancer screening. Countries that adopted widespread screening saw cervical cancer mortality drop by more than 70%. It remains one of the most successful cancer screening tests ever created.
First Chemotherapy Success
Sidney Farber used aminopterin to achieve temporary remissions in childhood leukemia. This proved that chemicals could fight cancer, launching the entire field of chemotherapy. Before this, surgery and radiation were the only options.
The National Cancer Act
President Nixon signed the National Cancer Act, dramatically expanding funding for cancer research through the National Cancer Institute. Often called the 'War on Cancer,' it accelerated decades of discovery in cancer biology and treatment.
Oncogenes Discovered
Scientists discovered that normal human genes (proto-oncogenes) could mutate into cancer-driving oncogenes. This fundamentally changed how we understand cancer: it is a disease of our own DNA, not an outside invader.
First Tumor Suppressor Gene Cloned
The retinoblastoma gene (Rb) became the first tumor suppressor gene to be cloned. This revealed the other side of cancer genetics: genes that normally prevent cancer can be lost or broken, removing the brakes on cell growth.
HPV Vaccine Approved
The FDA approved the first HPV vaccine (Gardasil). HPV causes nearly all cervical cancers and a significant portion of throat, anal, and other cancers. This was the first vaccine designed to prevent cancer, and it works. Countries with high vaccination rates have seen dramatic drops in HPV-related cancers.
Hallmarks of Cancer Updated
Hanahan and Weinberg published their updated 'Hallmarks of Cancer,' identifying the core capabilities that all cancers share. This framework, now expanded to include immune evasion and metabolic reprogramming, became the foundation for modern cancer research and drug development.
Lung Cancer Screening Proven
The National Lung Screening Trial showed that low-dose CT screening reduced lung cancer deaths by 20% in high-risk smokers. For the first time, there was a proven way to screen for the deadliest cancer in the world.
Nobel Prize for Immunotherapy
James Allison and Tasuku Honjo won the Nobel Prize for discovering checkpoint inhibitors, drugs that release the brakes on the immune system so it can attack cancer. Immunotherapy has transformed treatment for melanoma, lung cancer, kidney cancer, and many others.
CAR-T Cell Therapy Approvals
The FDA approved multiple CAR-T cell therapies, which reprogram a patient's own immune cells to hunt and destroy cancer. These treatments have produced complete remissions in patients with previously untreatable blood cancers.
Multi-Cancer Blood Tests and mRNA Vaccines
Multi-cancer early detection blood tests like Galleri entered large-scale clinical trials (NHS-Galleri, PATHFINDER). mRNA cancer vaccines moved into late-stage trials for melanoma and other solid tumors. The next era of cancer medicine is arriving.
How Cancer Develops
Understanding how cancer works is the first step toward understanding how to prevent it. Cancer is not random bad luck. It follows biological rules, and those rules create opportunities for prevention and early detection.
Modifiable Risk Factors
At least 40% of all cancers are attributable to factors you can change. That is not a small number. It means that for nearly half of all cancer cases, something could have been done differently. I want you to know what those factors are, how much they matter, and what the evidence actually shows.
Tobacco
30% of all cancer deathsTobacco is the single largest preventable cause of cancer. It causes at least 15 types of cancer, not just lung cancer. Smoking is responsible for roughly 80 to 85% of lung cancer cases and significantly increases risk for bladder, kidney, pancreatic, throat, and stomach cancers. Quitting at any age reduces risk. Even after 20 years of smoking, quitting produces meaningful risk reduction within 5 to 10 years.
Obesity and Excess Body Fat
Linked to 13 cancer typesExcess body fat increases risk for at least 13 cancers, including breast (postmenopausal), colorectal, endometrial, kidney, liver, pancreatic, and esophageal cancers. The mechanisms include chronic inflammation, elevated insulin and IGF-1, and increased estrogen production from fat tissue. Maintaining a BMI in the 18.5 to 24.9 range is one of the most impactful things you can do for cancer prevention.
Alcohol
No safe level for cancer riskThe relationship between alcohol and cancer is dose-dependent and begins with the first drink. Alcohol is a Group 1 carcinogen (same category as tobacco and asbestos). It increases risk for breast, colorectal, liver, esophageal, throat, and stomach cancers. Even one drink per day increases breast cancer risk by about 7 to 10%. The WHO, IARC, and American Cancer Society all agree: for cancer prevention, less is better, and none is best.
UV Radiation
Skin cancer is the most common cancerUltraviolet radiation from sunlight and indoor tanning causes the vast majority of skin cancers, including melanoma, the deadliest form. Indoor tanning before age 35 increases melanoma risk by 59%. Protection includes broad-spectrum SPF 30+ sunscreen, sun-protective clothing, seeking shade during peak hours (10 AM to 4 PM), and never using tanning beds. Regular skin self-exams using the ABCDE criteria help catch melanoma early.
Physical Inactivity
Exercise reduces risk for 7+ cancer typesRegular physical activity reduces risk for at least 7 cancer types, including breast, colorectal, endometrial, kidney, bladder, stomach, and esophageal cancers. The American Cancer Society recommends 150 to 300 minutes per week of moderate-intensity activity or 75 to 150 minutes of vigorous activity. Exercise works through multiple pathways: reducing inflammation, improving insulin sensitivity, supporting immune function, and helping maintain healthy body weight.
Chronic Infections
HPV causes ~35,000 cancers/year in the USSeveral infections directly cause cancer. HPV causes nearly all cervical cancers plus a significant portion of throat, anal, penile, and vaginal cancers. Hepatitis B and C cause liver cancer. H. pylori causes stomach cancer and gastric lymphoma. HIV increases risk for several cancers through immune suppression. The good news: HPV and hepatitis B vaccines prevent cancer, and H. pylori is treatable with antibiotics.
Ultra-Processed Food and Red/Processed Meat
Processed meat is a Group 1 carcinogenIARC classifies processed meat (bacon, hot dogs, deli meats) as a Group 1 carcinogen for colorectal cancer. Each 50g daily serving (about 2 slices of bacon) increases colorectal cancer risk by approximately 18%. Ultra-processed foods are associated with increased cancer risk through multiple mechanisms, including obesity promotion, high sodium, chemical additives, and displacement of protective whole foods. A diet rich in fiber, fruits, vegetables, and whole grains is consistently associated with lower cancer risk.
Environmental Exposures
Radon: ~21,000 lung cancer deaths/yearRadon is the second leading cause of lung cancer in the United States, responsible for an estimated 21,000 deaths per year. It is a naturally occurring radioactive gas that seeps into homes from the ground. Every home should be tested. Air pollution (fine particulate matter, PM2.5) is also an established lung carcinogen. Occupational exposures to asbestos, benzene, formaldehyde, and other chemicals contribute to cancer risk in certain industries. Simple actions like radon testing ($15 to $40) can identify and address a major risk factor.
Screening: What Works
Screening is not the same as diagnosis. A screening test looks for cancer (or precancer) in people who have no symptoms. When done correctly and for the right cancers, screening saves lives. But not all screening is created equal, and more screening is not always better. Here is what the evidence supports.
On the horizon: Multi-Cancer Early Detection Blood Tests
Tests like Galleri (by GRAIL) can screen for over 50 cancer types from a single blood draw by detecting cell-free DNA shed by tumors. The PATHFINDER study (2025, NEJM) showed that these tests can identify cancers that have no other screening method. The large NHS-Galleri trial (140,000 participants) has completed enrollment and follow-up, but full results have not yet been reported. While MCED is not yet standard of care, for many people who want an aggressive approach to cancer surveillance, this can be a good option. It is especially valuable for detecting cancers that have no other screening method available. I discuss this with patients who want to be proactive about early detection.
Emerging Detection and Treatment
Cancer medicine is advancing faster right now than at any point in history. Blood tests that detect dozens of cancers at once, personalized vaccines built from your tumor’s DNA, and immune therapies that can cure previously untreatable cancers are all either available today or in advanced clinical trials. Here is what I think you should know about.
Multi-Cancer Early Detection Blood Tests
Tests like Galleri detect cell-free DNA (cfDNA) shed by tumors into the bloodstream. A single blood draw can screen for signals from over 50 cancer types, including many that currently have no screening test (pancreatic, ovarian, liver, stomach). The PATHFINDER study showed that Galleri detected cancers across many organs with a positive predictive value of about 43%.
- Can detect cancer signals from 50+ cancer types with a single blood draw
- The NHS-Galleri trial (140,000 participants) has completed, but full results have not yet been reported
- For many people who want an aggressive approach to cancer surveillance, MCED can be a good option, especially for cancers with no other screening method
- Current limitations: sensitivity is highest for late-stage cancers and lower for early-stage cancers, where detection matters most
Liquid Biopsy
Liquid biopsy analyzes circulating tumor DNA (ctDNA), circulating tumor cells, or exosomes in a blood sample. Unlike MCED tests (which screen for cancer in healthy people), liquid biopsy is primarily used in patients already diagnosed with cancer to guide treatment decisions, monitor for recurrence, and detect resistance to therapy.
- FDA-approved tests exist for guiding treatment in advanced cancers (Guardant360, FoundationOne Liquid CDx)
- Used to identify targetable mutations when tissue biopsy is difficult or unavailable
- Increasingly used for monitoring minimal residual disease (MRD) after cancer treatment
- Research is expanding into earlier cancer detection, but this use is not yet validated for routine screening
Immunotherapy Revolution
Checkpoint inhibitors have transformed cancer treatment over the past decade. These drugs work by releasing the brakes on the immune system, allowing it to recognize and attack cancer cells. Before immunotherapy, metastatic melanoma had a 5-year survival rate of about 5%. Now, with checkpoint inhibitors, roughly 50% of patients with advanced melanoma are alive at 5 years.
- Checkpoint inhibitors (pembrolizumab, nivolumab, ipilimumab) are now approved for melanoma, lung cancer, kidney cancer, bladder cancer, head and neck cancer, and many others
- CAR-T cell therapy reprograms a patient's own immune cells to hunt cancer; FDA-approved for certain blood cancers with complete remission rates of 50 to 90% in some studies
- Not all cancers respond to immunotherapy; it works best in cancers with high mutation burden or specific immune markers
- James Allison and Tasuku Honjo won the 2018 Nobel Prize in Medicine for this discovery
mRNA Cancer Vaccines
The same mRNA technology used in COVID-19 vaccines is being adapted to fight cancer. These personalized vaccines are designed to teach the immune system to recognize and attack a patient's specific tumor mutations (neoantigens). Unlike preventive vaccines, these are therapeutic: they are given after cancer diagnosis to reduce recurrence.
- Moderna and Merck's mRNA-4157/V940 vaccine, combined with pembrolizumab, reduced melanoma recurrence by 44% compared to pembrolizumab alone in a Phase 2b trial
- Each vaccine is personalized: the tumor is sequenced, unique mutations are identified, and the mRNA is custom-built to target those specific mutations
- Phase 3 trials are underway for melanoma, and trials are expanding to non-small cell lung cancer and other solid tumors
- If successful, this approach could eventually be applied to many cancer types, fundamentally changing how we treat cancer after surgery
Full Body MRI Screening
Full body MRI uses magnetic resonance imaging to scan the entire body for abnormalities, without any radiation exposure. Unlike CT scans or PET scans, MRI uses magnetic fields and radio waves, making it safe to repeat regularly. This technology can detect soft tissue abnormalities, organ lesions, and masses that would not be found on any standard screening test.
- Radiation-free whole-body imaging that can be repeated safely on a regular schedule
- Can detect cancers and abnormalities in organs that have no other screening method, including pancreas, kidney, liver, and soft tissues
- Companies like Prenuvo and Ezra have made full body MRI more accessible, with scans typically taking 60 to 90 minutes
- For patients who want an aggressive approach to early detection, full body MRI is a valuable addition to standard screening. I recommend it for patients who want to be proactive about finding problems early
- Limitations include cost (not typically covered by insurance), potential for incidental findings that require follow-up, and the need for experienced radiologists to interpret whole-body scans
Targeted Therapy
Unlike traditional chemotherapy, which kills all rapidly dividing cells, targeted therapies attack specific molecular abnormalities that drive a particular cancer. These drugs are designed to hit cancer cells while sparing normal cells, resulting in fewer side effects and often better outcomes.
- Imatinib (Gleevec) transformed chronic myeloid leukemia from a fatal disease to a manageable chronic condition, with 10-year survival rates above 80%
- HER2-targeted therapies (trastuzumab, T-DXd) have dramatically improved outcomes in HER2-positive breast cancer
- PARP inhibitors benefit patients with BRCA-mutated breast and ovarian cancers
- Genomic profiling of tumors (next-generation sequencing) allows doctors to match patients with the targeted therapy most likely to work for their specific cancer