Immunotherapy is used for cancer most often when the disease is advanced, metastatic, or has come back after earlier treatment. But the timing depends heavily on the type of cancer, specific tumor characteristics, and whether other therapies have already been tried. In some cases, immunotherapy is now a first-line option given before anything else. In others, it’s reserved for patients whose cancer has stopped responding to chemotherapy.
Cancer Types That Qualify
Immunotherapy is approved for a wide and growing list of cancers. The types with the most established use include melanoma, lung cancer, bladder cancer, kidney cancer, head and neck cancers, liver cancer, and certain blood cancers like lymphoma and leukemia. But approvals extend well beyond those. Cervical, esophageal, stomach, uterine, breast, ovarian, prostate, and colorectal cancers all have immunotherapy options in specific situations.
The key detail: approval doesn’t mean every patient with that cancer type qualifies. Eligibility usually depends on the stage of the cancer, the results of biomarker testing on the tumor, and what treatments have already been tried. A person with early-stage breast cancer and a person with metastatic breast cancer face very different treatment paths, even though immunotherapy exists for both scenarios in certain cases.
Advanced and Metastatic Cancer
The most common scenario for immunotherapy is advanced or metastatic cancer, meaning the disease has spread beyond its original site or can’t be removed with surgery. This is where immunotherapy first proved its value, and it remains the setting with the broadest approvals.
Bladder cancer uses checkpoint inhibitors as a standard part of care in advanced or metastatic stages. Liver cancer is commonly treated with immunotherapy combinations paired with targeted therapies in advanced disease. Cervical cancer can be treated in recurrent, persistent, or metastatic settings. Head and neck cancers use checkpoint inhibitors for recurrent or metastatic disease. The pattern repeats across most approved cancer types: the further the disease has progressed, the more likely immunotherapy enters the picture.
First-Line vs. Later-Line Treatment
Whether immunotherapy comes first or after other treatments have failed is one of the most important timing decisions in cancer care. The answer often depends on a protein called PD-L1 that some tumors produce on their surface. Higher levels of PD-L1 generally predict a better response to checkpoint inhibitors.
In non-small cell lung cancer, for example, tumors with very high PD-L1 levels (50% or more of tumor cells) can receive immunotherapy as the very first treatment. When PD-L1 levels are lower, immunotherapy is typically combined with chemotherapy as a first-line approach, or reserved as a second-line option after chemotherapy alone has stopped working. Patients whose lung cancer progresses after initial chemotherapy can still benefit from immunotherapy regardless of their PD-L1 status.
For breast cancer, checkpoint inhibitors are typically used in the metastatic setting only when tumors express PD-L1. Stomach cancers follow a similar pattern, with immunotherapy offered when tumors show either PD-L1 expression or specific DNA repair-related biomarkers. Prostate cancer may respond to immunotherapy in advanced stages when tumors carry those same DNA repair biomarkers or have a high number of genetic mutations overall.
Before and After Surgery
Immunotherapy isn’t limited to late-stage disease. It’s increasingly used around the time of surgery in what doctors call neoadjuvant (before surgery) and adjuvant (after surgery) settings.
Before surgery, immunotherapy can shrink a tumor enough to make it easier to remove completely. After surgery, it helps eliminate microscopic cancer cells that might remain and could eventually cause a recurrence. Esophageal cancer, for instance, can be treated with checkpoint inhibitors before or after surgery. Bladder cancer has a long history of using a form of immunotherapy called BCG directly in the bladder for early-stage disease. Lung cancer now has approved regimens that include immunotherapy both before and after surgical removal of the tumor.
Combined With Chemotherapy or Targeted Therapy
Immunotherapy is frequently given alongside other treatments rather than on its own. In advanced squamous non-small cell lung cancer, combining chemotherapy with immunotherapy as a first-line approach has become standard practice, outperforming either treatment alone. The chemotherapy appears to help by breaking open cancer cells and releasing signals that make the immune system more responsive to the checkpoint inhibitor.
In liver cancer, immunotherapy is commonly paired with targeted therapies that cut off a tumor’s blood supply. In head and neck cancers, checkpoint inhibitors are sometimes combined with chemotherapy for recurrent or metastatic disease. The combination approach is expanding across cancer types because different treatments attack the cancer through separate mechanisms, making it harder for tumors to resist.
CAR-T Cell Therapy for Blood Cancers
A different branch of immunotherapy, CAR-T cell therapy, follows its own timing rules. This treatment involves collecting a patient’s immune cells, genetically engineering them to recognize cancer, and infusing them back into the body. It’s used primarily for blood cancers like certain lymphomas and leukemias.
CAR-T therapy is generally recommended when a cancer doesn’t respond to other treatments (called refractory disease) or comes back within 12 months after the first treatment, or after several prior treatments. It’s not a first-line option. Patients typically need to have exhausted other approaches before qualifying, because CAR-T therapy carries significant risks including severe immune reactions.
Who May Not Be Eligible
Not everyone with an otherwise qualifying cancer can safely receive immunotherapy. People with pre-existing autoimmune conditions present a particular challenge. Because checkpoint inhibitors work by releasing the brakes on the immune system, they can trigger dangerous flares of autoimmune diseases. Patients with autoimmune conditions are routinely excluded from clinical trials of these drugs.
Neurological autoimmune conditions like myasthenia gravis carry the highest risk, since a flare could be life-threatening. Patients with non-neurological, well-controlled autoimmune diseases may still be considered for immunotherapy, but require closer monitoring. Organ transplant recipients face similar concerns, as unleashing the immune system could trigger rejection of the transplanted organ.
What Treatment Looks Like in Practice
Immunotherapy is given as an intravenous infusion, typically on a set schedule. Common intervals range from every 2 weeks to every 6 weeks depending on the specific drug and dosing regimen. Some drugs offer flexible scheduling: the same checkpoint inhibitor might be given as a smaller dose every 2 weeks or a larger dose every 4 weeks, with similar effectiveness.
When two immunotherapy drugs are combined, the initial phase often involves infusions every 3 weeks for a set number of doses, followed by a maintenance phase with less frequent visits. Treatment duration varies widely. Some patients receive immunotherapy for a defined period (often one to two years), while others continue as long as the cancer responds and side effects remain manageable.
Side Effects and Their Timing
Immune-related side effects can appear at any point during treatment, and even after treatment ends. About 43% of patients experience at least one immune-related side effect within the first 6 months, and that number climbs to roughly 57% by the 2-year mark. This extended timeline means that new side effects can emerge months or even years after the last infusion.
The most common immune-related side effects involve the skin (rashes, itching), the gut (diarrhea, colitis), the thyroid (overactive or underactive function), and the liver (inflammation). Less common but more serious reactions can affect the lungs, heart, or nervous system. These side effects occur because the same immune activation that fights cancer can also cause the immune system to attack healthy tissues. Most are reversible when caught early, which is why ongoing monitoring continues well beyond the last dose.