ENIn bowel cancer, immunotherapy is not a general rule but a precise tool for a small group of patients, and an honest conversation about that helps more than hope in a drug that will not work in a given case. One test result decides: whether the tumour’s DNA repair system is broken.
Below: what MSI and dMMR mean in plain words, how the test is done, who receives bowel cancer immunotherapy in Germany, what others are offered, how a course runs and how it can continue at home. The method in general: cancer immunotherapy in Germany.
The one test that decides everything: MSI and dMMR
MSI and dMMR are two sides of one fault. Every cell has a system that finds and fixes DNA copying errors: mismatch repair, or MMR. When it is broken (dMMR), errors pile up and short repeating stretches of DNA become characteristically unstable: microsatellite instability, MSI.
This matters because a broken system fills the tumour with altered proteins, making it visible to the immune system. Checkpoint inhibitors, which release the brake on T lymphocytes, behave markedly differently in such tumours than in others. An MSS tumour, with an intact system, as a rule does not respond: a reason to discuss other treatment, not to seek a «stronger» immunotherapy.
It is checked by tumour immunohistochemistry, staining for the four MMR proteins, plus molecular MSI testing if the staining is unclear. German hospitals test every patient with this diagnosis, also because the result can point to hereditary Lynch syndrome and so to testing relatives.
The material comes from the existing paraffin block, tumour tissue kept after biopsy or surgery, so a repeat biopsy is usually unnecessary.
Who receives immunotherapy, and when
Immunotherapy is used above all in advanced dMMR or MSI-high (MSI-H) disease, where checkpoint inhibitors are considered first, including without chemotherapy. The German guideline recommends it; the EU has approved pembrolizumab alone and nivolumab with ipilimumab for first-line use. The same applies when disease returns after earlier treatment.
Second: immunotherapy before surgery for rectal or colon tumours with the same MMR defect. German tumour boards actively discuss it, because in some patients it changes the extent of surgery; in rectal cancer with a complete response, the German guideline advises forgoing the operation. Decisions are individual, within trials or a board-approved regimen, not on request: the drugs are not yet licensed for this use.
Immunotherapy is not indicated when the MMR system is intact, as in most bowel cancers. Here surgery, chemotherapy, targeted drugs against tumour blood vessels and, depending on mutation results, against EGFR, radiotherapy for rectal cancer and local techniques for liver metastases do the work: see bowel cancer treatment in Germany and stage 4 bowel cancer treatment.
What is established before treatment starts
Before treatment, these must be in hand: histology report with tumour type, MMR and MSI result, RAS and BRAF mutation testing, colonoscopy findings, chest, abdomen and pelvis imaging, and the CEA marker level as a monitoring baseline, as the German guideline on colorectal cancer sets out.
The patient is asked about illnesses already being treated, drugs that suppress the immune system, any organ transplant and any autoimmune disease. Some of these mean immunotherapy is not given or given under special management.
The case goes to a tumour board where oncologist, surgeon, radiologist, pathologist and radiation oncologist sit together. The patient gets a written plan, not a verbal promise, and is entitled to a second opinion from a German doctor.
How a course runs and what tolerability looks like
The drug is given by intravenous drip in a day unit, weeks apart: pembrolizumab, for example, every three or six weeks. Course length depends on the aim and on how the disease behaves; it is not fixed in advance for a year but reviewed against monitoring scans.
Side effects differ in nature from chemotherapy: an activated immune system can hit the bowel (diarrhoea, colitis), skin, thyroid and other endocrine glands, liver, less often lungs and heart. In bowel cancer, bowel inflammation needs special attention: it is easily mistaken for the disease itself.
The patient needs the on-call number, a list of signs that mean calling at once, and the schedule of tests and scans. Reacting early to a complaint usually means a short treatment pause; reacting late, hospital admission.
The trip, continuing at home, and cost
From abroad, the first trip takes several days: consultation, further tests, tumour board, start of treatment. Then patients either travel for each infusion, travel for monitoring and get the drug at home on the German plan, or stay for the whole course; continuing at home depends on the drug being available in their country.
The estimate depends on the drug and number of infusions, the day unit, tests and tumour board, and separately on molecular diagnostics if repeated in Germany. For the breakdown, see cost of immunotherapy in Germany.
Frequently asked questions
Does immunotherapy help if the MMR system is intact?
As a rule, no. A tumour with an intact MMR system (MSS) usually does not respond to checkpoint inhibitors, and in advanced disease these patients do not receive them. Other options remain: surgery, chemotherapy, targeted drugs, radiotherapy and local techniques for metastases, chosen on test results.
Can immunotherapy for bowel cancer be given without chemotherapy?
Yes: in advanced disease with a broken MMR system, this is the usual option. Pembrolizumab is used alone, and nivolumab with ipilimumab, another checkpoint inhibitor, without chemotherapy. Whether it suits a given case is decided by the tumour board, considering stage, earlier treatment and other illnesses.
Must the MSI test be repeated in Germany?
Not always. If the pathology report already shows an MMR staining or MSI result, the German oncologist assesses it with the other documents. The test may be repeated if the result is unclear or missing, using the existing paraffin block, so a new biopsy is usually unnecessary.
How AlenMed arranges bowel cancer immunotherapy in Germany
We first ask for the pathology report and whether the MMR system was tested; if not, we start there: without that result there is nothing to discuss. The case goes to oncologists at partner hospitals that treat colorectal cancer regularly, who say whether immunotherapy is indicated or another treatment fits better, before any figure is named. Then: a written plan, estimate, visa invitation, interpreter, accommodation.
The patient should plan for how many days the first trip takes, who answers questions after returning home and how test results from home reach the German doctor.
For information only, not an offer: the indication and regimen are decided by a doctor at an in-person consultation.
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