Theranostics is an emerging field that combines diagnostic imaging with targeted therapy to fight cancer. In practice, doctors use a "homing" molecule labeled with a radioisotope to first image the tumor and then to deliver radiation directly to those cancer cells (Dargan, 2024). This approach often uses lower overall doses of radiation focused on the tumor, which can spare healthy tissues and reduce side effects (Dahlstrom and Dargan, 2024). In simple terms, a patient may receive a PET scan using a tracer that binds a tumor-specific protein. If the scan is positive, the same targeting molecule is later attached to a therapeutic radioisotope to destroy the cancer cells. These "see and treat" strategies are already approved for some cancers and are being tested in others.
Theranostic treatments are currently used for specific cancers and show great promise. For example, neuroendocrine tumors (NETs) often overexpress somatostatin receptors. In 2018 the FDA approved 177 Lu-DOTATATE (Lutathera) for metastatic gastrointestinal and pancreatic NETs. Patients are first imaged with a somatostatin-based PET tracer, and if tumors light up, they receive the targeted 177 Lu therapy, often stabilizing disease for years (Dargan, 2024; Perkes, 2024). Similarly, advanced prostate cancer can be treated by targeting the PSMA protein. A PSMA PET scan identifies spread, and then 177Lu-PSMA-617 (Pluvicto) is given to kill prostate cancer cells. This new therapy, approved in 2022, can extend survival in men with metastatic disease (Dargan, 2024; Perkes, 2024). In both cases, theranostics delivers personalized, molecular therapy based on the patient's own tumor markers.
Theranostics also includes other established applications. For instance, differentiated thyroid cancer (papillary/follicular) naturally absorbs iodine. Doctors use radioactive iodine (I-131) to scan and then ablate remaining thyroid cells after surgery. This approach, first pioneered in the 1940s, is a classic theranostic treatment (Dargan, 2024). Likewise, bone metastases from prostate cancer can be treated with bone-seeking radiopharmaceuticals (e.g. radium-223, known as Xofigo) that deliver radiation to cancer in the bones while sparing other organs (Perkes, 2024). In short, any cancer with a known molecular target and tracer can potentially be imaged and treated via theranostics.
Cancers treated with theranostics
- Prostate cancer (metastatic): Uses PSMA-targeted PET and therapy. Patients undergo a PSMA PET scan, and if positive, receive a radioligand like 177 Lu- PSMA-617 (Pluvicto) that binds to prostate cancer cells and kills them (Dargan, 2024). This strategy is FDA-approved for castrate-resistant metastatic prostate cancer and has shown substantial responses (Dargan, 2024; Perkes, 2024). UCSF also uses radiopharmaceuticals like radium-223 (Xofigo) for prostate cancer that has spread to bone (Perkes, 2024).
- Neuroendocrine tumors (NETs): Include tumors of the pancreas, small intestine, and other sites that express somatostatin receptors. These are imaged with a somatostatin analog (e.g. 68 Ga-DOTATATE) and treated with 177 Lu-DOTATATE. Lutathera, the 177 Lu therapy, was FDA-approved in 2018 for metastatic NETs of the midgut and pancreas (Dargan, 2024). In clinical practice it can provide stable disease for many years with relatively mild side effects (Dargan, 2024; Perkes, 2024).
- Thyroid cancer: Differentiated thyroid cancers (papillary and follicular) concentrate iodine. Doctors perform diagnostic scans with radioactive iodine (I-131) and then give higher-activity I-131 to ablate residual thyroid tissue or metastatic disease. This theranostic approach has been standard care for decades. Patients with high-risk thyroid cancer after surgery are routinely treated with I-131 to eliminate remaining cancer cells.
- Other cancers (emerging): Research and early trials are expanding theranostics into additional tumor types. Studies are underway for melanoma, pancreatic, lung, kidney, breast and liver cancers (Turkbey, 2023; Perkes, 2024). For example, PET tracers targeting new proteins (like fibroblast activation protein, FAP) are being tested in pancreatic cancer. At UCLA, experts expect theranostic agents will soon be developed for kidney, breast, lung, pancreatic and liver cancers. Early clinical experience includes radio- labeled antibody therapies for lymphomas and radioactive MIBG for neuroblastoma, although these are less common. In all cases, the key is finding a tumor-specific molecule to target both imaging and treatment (Caldwell, 2024; Turkbey, 2023).
Theranostics represents a rapidly growing option in cancer care (Dargan, 2024). It is especially useful for patients whose tumors express known targets. By combining imaging and therapy, doctors can deliver precision treatment: "You see what you treat, and you treat what you see". This often means better outcomes and fewer side effects than conventional therapy (Dahlstrom, 2024; Dargan, 2024).
References
Becx, M. N., Minczeles, N. S., Brabander, T., De Herder, W. W., Nonnekens, J., & Hofland, J. (2022). A Clinical Guide to Peptide Receptor Radionuclide Therapy with 177Lu-DOTATATE in Neuroendocrine Tumor Patients. Cancers, 14(23), 5792. https://doi.org/10.3390/cancers14235792
Caldwell, A. (2024, November). The science behind theranostics. Mayo Clinic Magazine. https://mayoclinic.org/theranostics
Dahlstrom, E. (2024, October 21). What is theranostics? MD Anderson Cancer Center. https://mdanderson.org/theranostics
Dargan, R. (2024, March 21). Theranostics advances precision medicine for cancer patients. Radiological Society of North America (RSNA). https://rsna.org/theranostics
Perkes, C. (2024, March 20). Theranostics treatments for cancer underway at UCLA Health. UCLA Health News. https://uclahealth.org/theranostics
Turkbey, B. (2023, June 28). Theranostics and AI-The next advance in cancer precision medicine. NCI Cancer Data Science Pulse. https://datascience.cancer.gov/theranostics.