When cancer turns your world upside down, PET-CT can be a helpful guide, showing doctors exactly what's happening so you get the best, most personal care.

A cancer diagnosis can feel like being lost in a maze. You want answers, clear direction, and the best possible path forward. That's where PET-CT (Positron Emission Tomography – Computed Tomography) scans come in.

While conventional scans provide anatomical images, PET-CT explores the functional aspects of tissues and organs. This distinction is crucial in oncology, as it allows doctors to understand how cancer behaves at a cellular level, influencing treatment decisions and ensuring patients receive the care they need while avoiding unnecessary interventions.

Why cancer staging matters and how PET-CT enhances it

Accurately staging cancer is one of the first and most critical steps after diagnosis. Staging determines whether cancer is localised or has spread, directly influencing treatment decisions.

How PET-CT improves staging accuracy

PET-CT combines two types of imaging:

• PET (Positron Emission Tomography): Uses a small amount of radioactive glucose (FDG PET-CT) to highlight areas of high metabolic activity, often indicating cancer.
• CT (Computed Tomography): Provides detailed anatomical images of the body, helping pinpoint the exact location of abnormalities.

By merging these two technologies, PET-CT provides a more complete picture of cancer than CT or MRI scans which provide a detailed map of the body, showing the structure of organs and tissues, similar to looking at a road map. While this is useful for identifying the size and location of a tumour, it doesn’t tell doctors whether the tumour is actively growing or spreading.

This is where PET-CT offers a critical advantage. Think of it as not only showing the roads but also the traffic, where it's moving fast, where it's congested, and where it's unexpectedly busy.

Cancer cells behave very differently from normal cells, much like a traffic jam appearing in an unusual place. Healthy cells use glucose at a normal rate, like cars moving smoothly along a road. But cancer cells consume far more glucose and multiply rapidly, similar to an intersection suddenly filling with cars, even when there’s no obvious reason for congestion.

For example, in lung cancer, a traditional CT scan may reveal a small nodule in the lung. On its own, it's difficult to determine whether this is a harmless scar from a past infection or an early-stage tumour. However, when a PET-CT scan is performed, the cancerous cells will light up because they absorb significantly more glucose than surrounding healthy lung tissue. This helps doctors decide whether the nodule needs immediate treatment or can be monitored over time.

By providing structural and metabolic information, PET-CT ensures that doctors get the whole picture, not just where the cancer is but also how aggressively it behaves.

From staging to strategy: How PET-CT informs treatment decisions

Once cancer has been staged, PET-CT plays a key role in planning treatment. The more precisely doctors can identify the cancer’s location and activity, the better they can tailor treatment to each patient’s needs.

How PET-CT helps with treatment planning

• Guiding surgery: In some cancers, PET-CT helps surgeons determine whether an operation is the best course of action. If cancer has spread beyond a specific area, surgery may not be the most effective option, and other treatments may be recommended instead.
• Optimising radiation therapy: PET-CT helps oncologists target tumours more accurately while sparing healthy tissue, reducing side effects.
• Refining chemotherapy and immunotherapy plans: Not all cancers respond to the same treatments. PET-CT helps determine which tumours are more aggressive and likely to respond to certain drugs, allowing for personalised therapy adjustments.

For instance, in melanoma, PET-CT can detect small metastases (spread of cancer cells) in lymph nodes or distant organs that may not be visible on standard CT or MRI scans. A patient may have what appears to be a localised skin tumour, and based on traditional imaging, surgery might seem like the best option. However, PET-CT can reveal that the cancer has already spread to other parts of the body, changing the treatment plan entirely. Instead of undergoing surgery alone, the patient may receive targeted therapy or immunotherapy to address the cancer more effectively.

By showing not just where cancer is located, but how active it is, PET-CT helps doctors choose the right treatment approach and avoid unnecessary procedures.

Reducing unnecessary treatments

One of PET-CT's greatest advantages is its ability to prevent patients from undergoing unnecessary treatments that may not be beneficial. Cancer treatment often involves a combination of surgery, chemotherapy, and radiation, but not all patients need every type of treatment. PET-CT ensures that doctors make the most informed decisions possible.

How PET-CT prevents overtreatment

• Avoiding unnecessary surgery: If a PET-CT scan shows that a patient’s cancer has already spread to distant organs, doctors may choose a more effective systemic treatment instead of putting the patient through an operation that wouldn’t provide long-term benefits.
• Reducing unnecessary chemotherapy: In some cases, PET-CT reveals that a tumour is responding well to initial treatment, allowing doctors to adjust or shorten the treatment plan, reducing exposure to chemotherapy’s side effects.
• Preventing ineffective radiation therapy: If a PET-CT scan shows that a tumour is inactive or shrinking, doctors can avoid continuing radiation treatments that may not be needed.

For example, in patients with lymphoma, PET-CT is often used after a few cycles of chemotherapy to determine whether the treatment is working. If the scan shows that the tumour is no longer metabolically active, doctors may reduce or stop chemotherapy early, sparing the patient from unnecessary side effects.

Monitoring progress and detecting recurrence

A major hurdle in cancer treatment is determining whether a therapy is achieving its intended effect. PET-CT provides a powerful real-time feedback mechanism, allowing doctors to evaluate progress and adjust treatment strategies accordingly.

Key benefits of PET-CT in monitoring treatment:

• Detecting early signs of success (or resistance): If a tumour is shrinking, doctors know the treatment is effective. If not, they can switch strategies before valuable time is lost.
• Avoiding unnecessary side effects: If PET-CT confirms that a tumour is no longer metabolically active, patients may be spared additional rounds of chemotherapy or radiation that are no longer needed.
• Detecting recurrence sooner: PET-CT can pick up small recurrences before symptoms appear, leading to earlier intervention and better outcomes.

For instance, a patient undergoing chemotherapy for breast cancer may receive a PET-CT scan midway through treatment. If the scan shows a strong response, the doctor might reduce the chemotherapy duration, limiting side effects without compromising effectiveness.

This proactive approach ensures that patients receive precisely the care they need, nothing more, nothing less.

A smarter, more personalised approach to cancer care

PET-CT has become a gold standard in cancer care in many parts of the world. However, in South Africa, access has historically been limited. This is now changing as more hospitals and specialised cancer centres invest in PET-CT technology, ensuring that patients receive the most precise and personalised care possible.
With PET-CT, doctors can make informed decisions at every stage of a patient’s cancer journey. These scans help personalise care, improve outcomes, and spare patients from unnecessary procedures and side effects.
For anyone facing cancer, knowledge is power. PET-CT provides that knowledge, ensuring that every step of the journey is guided by the most accurate and up-to-date information available. If you or a loved one has been diagnosed with cancer, speak to your doctor about whether a PET-CT scan could be part of your treatment plan.

At Life Healthcare, we are committed to providing world-class medical imaging and cancer care, ensuring that South African patients have access to the latest advancements in nuclear medicine.
To learn more about PET-CT at Life Healthcare, click here.