Locoregional therapy is a specialized cancer treatment focusing on a specific, confined area within the body. It delivers treatment directly to the tumor site and its immediate surroundings, aiming to eliminate or control cancer cells within that defined region. This approach is often used when cancer is limited to one organ or a small number of areas, minimizing impact on the entire body.
Targeted Treatment Approach
The fundamental principle behind locoregional therapy involves targeting and treating cancer cells within a specific organ or body region. This approach minimizes the impact on healthy tissues located elsewhere in the body. Unlike systemic therapies, such as chemotherapy or immunotherapy, which circulate throughout the bloodstream, locoregional treatments are confined to a precise area.
The primary goal of locoregional therapy is to achieve local disease control, preventing cancer from growing or spreading within the treated area. By focusing treatment directly on the tumor, clinicians can deliver higher concentrations of therapeutic agents or energy, increasing effectiveness against cancer cells. This localized delivery also helps reduce systemic side effects, preserving the function of healthy organs and tissues outside the immediate treatment zone.
Primary Methods of Locoregional Therapy
Locoregional therapy encompasses various distinct treatment modalities, each designed to specifically target cancerous cells within a localized area. These methods leverage different scientific principles to destroy or control tumor growth.
Surgery
Surgery involves the physical removal of the tumor and a margin of surrounding healthy tissue. This method aims to excise the entire cancerous mass, often including nearby lymph nodes if there is a risk of spread. The extent of surgical removal depends on the tumor’s size, location, and type, with the goal of achieving clear margins, meaning no cancer cells are found at the edges of the removed tissue.
Radiation therapy
Radiation therapy uses high-energy rays to damage the DNA of cancer cells, preventing them from growing and dividing. External beam radiation delivers radiation from a machine outside the body, precisely directing beams to the tumor. Internal radiation, or brachytherapy, involves placing radioactive sources directly inside or near the tumor, allowing for a highly concentrated dose of radiation to the affected area while sparing surrounding healthy tissue. Stereotactic body radiotherapy (SBRT) is a form of external beam radiation that delivers high doses in a few fractions, accurately targeting the tumor while limiting exposure to adjacent non-target organs.
Interventional radiology techniques
Interventional radiology techniques involve minimally invasive, image-guided procedures to treat tumors. Embolization procedures block the blood supply to a tumor, starving it of oxygen and nutrients. For example, Transarterial chemoembolization (TACE) delivers chemotherapy drugs directly to the tumor via its blood supply, then blocks the vessels feeding it.
Ablation techniques destroy tumors using extreme temperatures or chemicals. These include radiofrequency ablation (RFA) and microwave ablation, which use heat, and cryoablation, which uses subfreezing temperatures. Percutaneous ethanol injection (PEI) involves injecting ethanol directly into the tumor, causing tissue destruction.
Regional chemotherapy or perfusion
Regional chemotherapy or perfusion involves directly delivering chemotherapy drugs to a specific organ or body part. Isolated limb perfusion, for example, delivers high doses of chemotherapy to a limb affected by cancer while minimizing systemic exposure. Hepatic arterial infusion delivers chemotherapy directly into the liver’s arterial blood supply, which primarily feeds liver tumors, allowing for higher drug concentrations at the tumor site with fewer systemic side effects. This approach takes advantage of the fact that liver tumors derive most of their blood supply from the hepatic artery, providing a direct pathway for drug delivery.
Conditions Where Locoregional Therapy is Applied
Locoregional therapy is frequently employed when cancer is confined to a specific organ or a limited number of sites, making it amenable to localized intervention.
For example, in hepatocellular carcinoma (HCC), a common liver cancer, locoregional therapies are integral to management, particularly for patients not suitable for surgery. Ablative therapies like radiofrequency ablation (RFA) or microwave ablation are often first-line treatments for very early-stage HCC, aiming for curative outcomes. Transcatheter techniques, such as transarterial chemoembolization (TACE) or radioembolization, benefit patients with intermediate-stage HCC. These therapies can be used with curative intent, to reduce tumor burden for transplant criteria (downstaging), or to control tumor growth while awaiting a liver transplant (bridging therapy).
Locoregional approaches are also applied in early-stage lung cancer, where stereotactic body radiation therapy (SBRT) can precisely target small tumors, particularly in patients who cannot undergo surgery. Similarly, in certain breast cancers, localized radiation therapy is used after lumpectomy to reduce the risk of local recurrence. In cases of melanoma that have spread to a limb, isolated limb perfusion can deliver high concentrations of chemotherapy directly to the affected area.
Factors Influencing Treatment Choice
The selection of a specific locoregional therapy, or a combination of therapies, is a highly individualized decision. This choice is based on a thorough assessment of several patient- and tumor-specific factors.
Tumor characteristics, including its size, exact location, and cancer stage, influence the treatment approach. A smaller, well-defined tumor might be suitable for ablation, while a larger or more complex tumor might require surgical resection or a combination of therapies. The patient’s overall health status, including any pre-existing medical conditions or comorbidities, also plays a role in determining tolerance for specific procedures.
Previous treatments received by the patient are considered, as they can impact the effectiveness and safety of subsequent locoregional therapies. The expertise and recommendations of a multidisciplinary team, including oncologists, surgeons, interventional radiologists, and radiation oncologists, guide the treatment plan. This collaborative assessment ensures that the chosen therapy is tailored to maximize efficacy while minimizing risks for each patient.