Endoscopic and drug therapy

The complete endoscopic removal of a colorectal cancer can be reliably performed at an early stage using various endoscopic techniques. Early stages are tumours that only affect the upper parts of the intestinal wall (mucosa, submucosa). These are so-called T1-stages. In these cases, the endoscopist can lift the tumour from the muscle layer by injecting fluid into the intestinal wall and remove the tumour reliably and safely with a sling (mucosectomy), needle knife (ESD) or a whole wall resection (FTRD). If the pathologist evaluates the preparation and there are no risk factors, a regular check-up is sufficient in the further course. In the case of risk factors, i.e. a low differentiation of tumor tissue (G3, G4), lymph vessel infiltration or blood vessel invasion, the patient must be operated according to oncological criteria.

In the drug treatment of cancer of the colon and rectum, a basic distinction is made between cancer of the colon (colon carcinoma) and cancer of the rectum (rectal carcinoma).

Treatment of colon cancer

• If the tumour has been completely removed and no lymph nodes are affected, regular check-ups are sufficient.
• If the tumour has been completely removed and lymph nodes are affected: follow-up with adjuvant chemotherapy every two weeks for six months (twelve cycles) on an outpatient basis.

Treatment of rectal cancer

• All rectal carcinomas that reach (T2) or exceed (T3) the muscle layer in depth, or all rectal carcinomas with lymph node involvement (N+) should receive combined chemotherapy with radiation (radiochemotherapy) before surgery. In certain cases, short-term radiation alone can also be used.
• After neoadjuvant radiochemotherapy, adjuvant chemotherapy is indicated independently of the postoperative tumor stage (i.e. also for complete remission or UICC stages I and II).
• Rectal cancers (T2N0, T3N0, N+) that have not received neoadjuvant radiochemotherapy or short-term radiotherapy should receive adjuvant radiochemotherapy.
• After incomplete removal of the tumour (R1-resection) or intraoperative tumour rupture, radiochemotherapy should be performed postoperatively if no neoadjuvant radio(chemo)therapy has been performed before.

The following treatment groups/therapy goals are distinguished:

1. Patients with primarily resectable liver and/or lung metastases should be operated on primarily. A neoadjuvant systemic therapy of resectable liver metastases may be considered in justified exceptional cases.
2. Patients with an indication for intensified systemic therapy. In case of primary ireresectability but potential resectability an intensified systemic chemotherapy should be performed. This also applies to patients who are not resectable, but who show symptoms due to their metastases or the tumour shows a rapid progress. Further therapeutic options are the local treatment of liver metastases by laser-induced thermotherapy (LITT) or selective intrahepatic radiotherapy (SIRT), which can also be combined with chemotherapy.
3. Patients with multiple metastases without an option for resection after metastasis regression, without tumour-related symptoms or organ complications and/or severe comorbidity should receive less intensive chemotherapy.

Chemotherapy for colorectal cancer is given according to standard protocols that have been tested and usually include combinations of chemotherapeutic agents. In more advanced and initially incurable stages, the chemotherapy protocols can be combined with antibody therapies that influence growth factors. In this case, antibody therapy is carried out in dependence on certain tumour markers which the colon cancer can develop (e.g. KRAS, NRAS). A selected combination of therapies should initially be continued indefinitely if the tumour progression is stable, depending on tolerance. In this way, the tumour therapy can be individualised in the course of the disease. In contrast to a conceptual therapy break, there may be short-term interruptions of the chemotherapy due to the personal life situation of the patient (e.g. holidays). In this case, short-term therapy breaks are justifiable.

The choice of second- and third-line therapy depends on previous therapies and the time without therapy as well as on the individual patient situation and the respective therapy goal. While in first-line therapy options of shortening the duration of therapy or "stop-and-go" strategies are currently being considered (see above), the principle that therapy should be carried out until the disease has progressed continues to apply to second- and third-line therapies.