The PET scan is a highly tried and tested imaging technique for studying the spread of cancer. It allows doctors to detect a tumor in its early stages and to discover, with great accuracy, exactly what organs are affected. Therefore, it is an indispensable tool to be used before proceeding to the surgical removal of a tumor. Results from PET scans help with a better treatment approach and increase the chances of a cure.
Doctor Aurora Crespo, head of the Nuclear Medicine Unit of the Oncology Department at Quironsalud Torrevieja Hospital, working with a Multidisciplinary Oncology Professorship at UCAM, has presented her thesis in which she analyzes the genes that contribute most to FDG uptake in PET scans for patients with metastatic tumors. The study’s conclusions reveal that the technique of using a PET scan with glucose helps to predict a tumor’s behavior when faced with chemotherapy. To accomplish the aforementioned, microarray gene expression (MAGE) has been used in combination with PET scan imagery.
The thesis is based on the preferential consumption of glucose by cancer cells and how a glucose-based radiopharmaceutical would concentrate specifically around malignant tumors. “When a case of cancer progresses,” the doctor explains, “secondary tumors –or metastases– can crop up.” To undertake this process, the tumor cell needs more energy than the normal cell, and that energy is obtained primarily through the metabolism of glucose (glycolysis). In general, the tumor cell uses more glucose than the normal cell because it needs more energy to meet its goal. The most novel contribution of Dr. Crespo’s work has consisted of designing a genomic signature identifying the genes responsible for an increased consumption of glucose as a result of metastasis, allowing for the in-depth study and understanding of the most relevant metabolic pathways that participate in glucose uptake.
“Active tumors retain the radiopharmaceutical known as FDG, a radiolabeled glucose, which allows for distinction in the PET image from the rest of the healthy tissues. If, in the first few days of treatment, that signal turns off, it means that the treatment is affecting the tumor and is going to end up destroying it,” explains the doctor. Thus, if the treatment is not effective, it can be interrupted in order to avoid toxicity and seek another, more effective approach.
The results of Dr. Crespo’s study have shown that glucose (FDG) can mark cancer’s biological, metabolic, and proliferative activity. Thus, the PET scan can provide valuable information to determine whether a case of cancer will respond well to treatment or not. If the chemotherapy is going to be effective, it is going to be possible to see decreased FDG uptake on the PET scan and, thus, predict whether a tumor will respond well to treatment just a few days after having given the first dose.
This early response allows us to predict results and, just a few weeks after administering treatment, to see if the tumor is responding to the drug that has been used. Taking into account that, currently, the response to treatment is determined two or three months after starting chemotherapy, these results are quite encouraging.
The Importance of the PET Scan in Cancer Treatments
Several studies have shown the great clinical impact of the PET technique in oncology, a fundamental tool in the diagnosis of cancer because it identifies where the disease is located and how widespread it is. In patients with colorectal cancer, lung neoplasm, malignant melanoma and lymphoma, this technique may change the therapeutic strategy to be followed in up to 40% of the cases. Thus, this metabolic technique helps doctors to select the optimal treatment for each case, reducing the number of aggressive diagnostic procedures and avoiding unnecessary surgeries.