The World Health Organization (WHO) observed World Cancer Day on August 1 to raise awareness about lung cancer and the need for increased research funding.
In Kenya, lung cancer has significant contribution to the cancer burden, with approximately 1,200 new cases and over 800 deaths each year.
More than 60 per cent of those affected are under 70 years and majority (70-80 per cent) are diagnosed at an advanced stage, according to the National Cancer Institute of Kenya.
With effective medical imaging carrying potential to enhance survival rates for lung cancer, Dr Solomon Mutua, a Clinical Oncologist at The Nairobi West Hospital, discusses the nuances of lung cancer imaging, delving into the role of chest CT scans in early lung cancer detection, importance of PET in lung cancer staging, and why it’s important to seek a second opinion to avoid diagnostic errors.
A chest x-ray is a quick and cost-effective imaging test for the lungs, commonly used for initial examinations. However, it has limitations compared to a chest CT scan.
While a chest x-ray can identify some lung tumors, it may miss small tumors present in the early stages of lung cancer and is less effective at assessing cancer spread.
In contrast, a chest CT scan provides detailed images by taking multiple pictures of the lungs and chest, compiling them into a comprehensive view. This detailed imaging allows for the detection of very small nodules and is especially useful for diagnosing lung cancer at its most treatable stage.
If a chest x-ray or chest CT scan reveals suspicious findings, a PET scan is the next appropriate step. PET (positron emission tomography) uses a radioactive tracer to visualize molecular activity in the body. Typically, a PET scan is performed alongside a chest CT scan.
The two scans are fused to provide combined information for more accurate interpretation. The Nairobi West Hospital now offers an AI-enhanced PET/CT scan.
A PET scan can detect cancer in lymph nodes and organs that appear normal on a chest CT scan. Since PET scans cover a larger area of the body, from the skull to the thighs, they are particularly effective at identifying metastatic disease.
However, PET/CT interpretation is complex and requires expertise to avoid false positives or negatives.
For example, the tracer used in PET can help an interpreting radiologist distinguish between benign (noncancerous) and malignant (cancerous) masses. This is of course extremely valuable.
But – if the radiologist does not have adequate training and extensive experience diagnosing lung cancer, there’s an increased risk for misdiagnosis. Ensuring your PET and CT chest scans are interpreted by a radiology subspecialist can help prevent errors.
A PET scan is invaluable for staging lung cancer as it detects changes in glucose metabolism, which is crucial for accurate staging. It is usually performed before treatment to provide the most precise staging and to check for cancer spread to lymph nodes or other organs not visible on a chest CT scan. Accurate detection of cancer spread is critical for effective treatment planning.
By detecting minute changes in glucose metabolism, a PET scan can pick up on positive treatment effects even before the tumour starts to shrink. So, when we use a PET scan for lung cancer treatment management, we’re able to gauge treatment effectiveness earlier and more accurately than we would be able to with a chest CT scan.
Upon completion of treatment, the tumours may not completely disappear on a CT scan. In this situation, a PET scan can determine if there is still viable cancer in residual tumours that are picked up on with the chest CT scan. This allows doctors to decide if more treatment is needed.
By detecting increased tumor metabolism or tumor sites that are not visible via CT, a PET scan can also let us know when a tumor is not responding to treatment sooner than a chest CT scan is able to. In such scenarios, doctors can quickly change the treatment as needed.
With the advancement of lung cancer treatment, many more options are available to patients now than a decade ago. And, thankfully, doctors can even monitor the success of a medication with PET/CT scans. But again, interpretation can be challenging, requiring a very specialised set of skills. An expert second opinion can make a big difference for patients.
Benign lung nodules can look similar to lung cancer on a chest CT scan. This puts patients at risk of a false-positive. Or, the reverse may happen – a radiologist might dismiss a malignant mass as a benign mass. Either or has negative consequences. This is another reason that patients should seek a second opinion on their chest CT scan.
Another challenge is that lung cancer can be hidden within lung inflammatory changes or scarring. In this situation, a lung PET scan can substantially expedite the diagnosis and management by showing high glucose metabolism in areas of concern and by guiding biopsy to the area of concern.
Having a subspecialist look at your scans helps ensure that situations such as these will be recognised and handled appropriately.
Given the complexity of interpreting chest CT and PET scans, it is best to have these images reviewed by a subspecialty radiologist. Seeking a second opinion ensures the most accurate information and optimal care.
If CT scan results are inconclusive, consider requesting a PET/CT scan. Early and accurate screening can significantly reduce lung cancer-related deaths, and increased awareness about the capabilities of medical imaging empowers patients to seek timely and appropriate care.
