Nuclear Medicine in Oncology: Lighting the Way in Cancer Diagnosis & Therapy

Hello LinkedIn community! Whether you're a fellow healthcare professional or someone curious about medical advancements, this issue of the newsletter dives into the fascinating world of nuclear medicine and its pivotal role in fighting cancer. We'll keep it straightforward, blending science with real-world insights, so everyone can follow along. Let's explore how tiny amounts of radioactive materials are saving lives—one scan at a time.

Imagine being able to see cancer cells “light up” inside the body—before they cause symptoms, before they grow bigger, and before they spread. This is what nuclear medicine makes possible.

The Story Begins with a Tracer

The foundation of nuclear medicine goes back to a groundbreaking idea from Hungarian chemist George de Hevesy in the early 20th century, a Nobel Prize–winning scientist and also widely recognized as the "father of nuclear medicine"

·        Hevesy discovered that minute quantities of radioactive compounds (radiopharmaceuticals) / radioactive tracers could be used to follow chemical processes inside living beings—just like adding a drop of dye to water to see where it flows.

·        In his famous experiment, he used tiny amounts of radioactive isotopes to study how plants absorbed nutrients.

·        This “tracer principle” is still the basis of nuclear medicine today: ➡️ Use a safe radioactive compound (called a radiotracer) that behaves like natural substances in the body. ➡️ Track its path with special cameras. ➡️ Learn how organs and disease’s function—from the inside out.

What is Nuclear Medicine?

Nuclear medicine is a branch of medical imaging and therapy that uses small amounts of radioactive materials (called radiotracers) to diagnose and treat diseases, especially cancer. These tracers are injected, swallowed, or inhaled, and they target specific organs or tissues. Special cameras detect the radiation emitted, creating images that show how your body is functioning at a molecular level—not just its structure.

Unlike X-rays or MRI that show body structures, nuclear medicine looks at how the body works at a cellular level - like how cells are metabolizing or if a tumor is active.

·        Small amounts of radioactive tracers (safe, medical-grade) are used.

·        Special scanners detect these tracers and create detailed images.

·        The result? Doctors don’t just see where something is, but also how active it is.

It has two main arms:

1.     Imaging using:

a.      Conventional Nuclear Medicine (Gamma Camera / SPECT)

b.     Molecular Imaging (PET-CT)

2.     NM therapy or now popularly known as Theranostics (Diagnosis + Therapy with the same molecule)

Conventional Nuclear Medicine – The Gamma Camera Era

• Uses gamma cameras to detect radioactive tracers and Produce images of organ function.
• Common tracers: 99mTc (Technetium-99m) based RPs → most widely used isotope globallyThe workhorse tracer, used in over 80% of procedures. Used for bone scans, renal scans, cardiac scans, thyroid scans. Iodine I-123 / I-131: Benign and malignant thyroid diseases - Targets thyroid tissue. In diagnosis, it scans for thyroid cancer; in therapy, higher doses destroy cancerous cells.
• Helps in cancer by: Detecting bone metastases (spread of cancer to bones). Assessing thyroid cancer.

PET-CT – The Molecular Imaging Revolution

PET-CT combines positron emission tomography (PET) with CT.

• Shows both function (PET) and structure (CT) in one scan.
• Uses radiotracers that mimic natural body chemicals or target receptors in various physiological and patholigcal conditions.

Common PET tracers in cancer:

• 18F-FDG (Fluorodeoxyglucosewith F-18) → Mimics sugar, detects sugar-hungry cancer cells and used in most of the cancers including lung, lymphoma, breast and colorectal cancers.
• 68Ga-PSMA → prostate cancer.
• 68Ga-DOTATATE → neuroendocrine tumors.
• FES (Fluoroestradiol) → breast cancer (estrogen receptor imaging).

Role in Cancer Diagnosis 👉 PET-CT is often called the GPS for cancer, guiding doctors at every step:

·        Early detection: Using various metabolic and functional processes such as FDG PET scan targetting glucose metabolism: Cancer cells consume more energy—nuclear scans pick this up early.

·        Accurate staging: Shows if cancer has spread.

·        Treatment planning: Helps doctors decide surgery, chemotherapy, or radiation approaches.

·        Treatment Response Assessment: Shows if cancer is responding or not to treatment

·        Follow-up: Detects recurrence earlier than most tests.

Role in Cancer Therapy: 🎯 Theranostics – Treat What You See and Diagnose and Treat in One Go

Nuclear medicine is not just about diagnosis—it can also treat cancer.

Theranostics = Therapy + Diagnostics.

Uses the same molecule for both diagnosis and treatment, just with different isotopes, For e.g. 68GaPSMA for Prostate cancer staging using PET CT and 177LuPSMA PRLT therapy for progressive and metastatic CRPC prostate cancer. It's personalized medicine at its best: "See it, then zap it."

·        Targeted therapy: Radioactive medicines deliver treatment directly to cancer cells while sparing most healthy tissue.

·        Used in thyroid cancer, prostate cancer, lymphomas, and neuroendocrine tumors.

·        Think of it as a smart bomb—precise and powerful.

📈 Clinical impact:

·        Lu-177 PSMA therapy has shown 40% reduction in risk of death in advanced prostate cancer (VISION trial).

·        NETTER-1 trial showed 79% progression-free survival improvement with Lu-177 DOTATATE in neuroendocrine tumors.

In India, more than 10,000 Lu-177 therapies have been performed in the last 5 years, positioning the country as a regional hub for theranostics.

📊 The Numbers – Nuclear Medicine Worldwide : Nuclear medicine is booming, driven by aging populations and cancer rises.

·        Diagnostic Nuclear Medicine: ~40 million (4 crore) procedures annually worldwide.

o   USA: ~20 million scans/year.

o   India: ~0.5–1 million scans/year (rapidly growing).

·        Therapeutic Nuclear Medicine:

o   In 2023, over 100,000 theranostic procedures were performed globally, with rapid growth in prostate and neuroendocrine treatments.

o   Growing at 10–15% annually worldwide.

o   Theranostics centers expanding rapidly, especially in prostate and neuroendocrine cancer treatment.

·        Market value:           

o   $10.19B in 2024, projected to $42B by 2032 (CAGR ~19%). Theranostics segment growing fastest at 13-15% CAGR.

o   USA: $5.12B in 2023, to $16.85B by 2033 (CAGR 12.6%). High adoption of PET-CT (over 2,000 scanners).

o   India: Rapid growth with 300+ centers. ~1-2 million procedures/year. Market to $1.07B by 2030 (CAGR 10.9%), fueled by affordable tech and rising cancer cases (1.4M new/year).

Therapeutic procedures (like radioiodine therapy) grew 20% globally post-COVID, with India seeing 25% annual increase due to better access.

Future: Bright and Innovative

By 2030, theranostics could dominate cancer care. Prospects include:

·        Expansion to Lung, breast, brain, pancreatic, and ovarian cancers.

·        Alpha emitters (like Ac-225) for resistant cancers.

·        AI-integrated imaging for smarter imaging interpretation, predictive response modeling and faster, more accurate targeting.

·        Combination with immunotherapy.

·        ImmunoPET tracers: tracking immune checkpoint inhibitors in real time

·        Personalized dosimetry: tailoring therapy dose to maximize tumor kill & minimize toxicity

Challenges: Supply chain for rare isotopes, but advancements in cyclotron production are helping.

🚫 Myths vs Facts

• Myth: Nuclear medicine is unsafe because of radiation. ✅ Fact: Radiation doses are carefully regulated, often equal to or less than a CT scan. It is safe, regulated, and used worldwide for decades. Doses are low— a PET scan is like 2-3 years of natural background radiation. Tracers decay fast (hours/days), and benefits outweigh risks.
• Myth: The radioactivity stays in your body forever.
• ✅ Fact: Most tracers are eliminated naturally within days. No long-term buildup.
• Myth: It's painful or invasive.
• ✅ Fact: Just an IV injection or pill—less invasive than surgery, no pain beyond a needle prick.
• Myth: It causes cancer
• ✅ Fact: Risk is minimal (1 in 10,000 for diagnostics). It's used to fight cancer, not cause it.
• Myth: Only for end-stage cancer.
• ✅ Fact: Great for early detection and monitoring, improving survival rates by 20-30% in many cases.
• Myth: PET-CT replaces all other scans. ✅ Fact: Different scans answer different questions. PET-CT complements, not replaces.
• Myth: Once treated with radiotheranostics, you “glow” or are radioactive. ✅ Fact: The radiation is medical-grade, controlled, and leaves the body safely.

Why It Matters for Patients

For patients, nuclear medicine means:

·        Less invasive tests

·        More confidence in diagnosis

·        Tailored Personalised treatment

·        Better chances of cure and survival

📝 Take-Home Messages

·        Nuclear medicine is not science fiction—it’s science saving lives daily.

·        It allows doctors to see cancer earlier, track it better, and treat it smarter.

·        From Hevesy’s tracer principle to modern PET-CT and theranostics, the field has grown into a cornerstone of cancer care.

·        India is catching up fast with global trends, and access is expanding.

·        The future promises personalized, precise cancer care with nuclear medicine at its heart.

·        Bust the myths: It's safe, precise, and life-saving.    

Nuclear medicine is like a torchlight in the dark tunnel of cancer—helping doctors see clearly, act precisely, and give patients hope.

Nuclear medicine is not just science—it’s a blend of technology and compassion, guiding modern cancer care.

“Next time you hear about PET scans or targeted radiotherapy, remember—they’re part of a powerful field called nuclear medicine that combines vision with cure.

Have you or your loved one ever had a PET-CT or heard about nuclear medicine therapy? Share your thoughts in the comments.”

By Dr. Aashish Gambhir, Director & Head, Nuclear Medicine

Andromeda Cancer Hospital