This is an explorative, phase I clinical trial. The aim of this study is to establish the safety and efficacy of treating patients with early colorectal cancer with calcium electroporation prior to intended curative surgery.

This is an explorative, phase I clinical trial. The aim of this study is to establish the safety and efficacy of treating patients with early colorectal cancer with calcium electroporation as a down staging and immune-response enhancing treatment prior to intended curative surgery. The study involves recruitment of patients with histologically verified rectal and sigmoid colon cancer with no indication for neoadjuvant chemoradiotherapy (experimental or standard care based) prior to intended curative surgery. In total the study will involve 24 patients, of these, 12 patients with rectal cancer and 12 patients with sigmoid colon cancer.

In relation to the intervention, clinical examination, blood samples, biopsies and questionnaires will be collected to evaluate safety, tumor respons and immunologic response to the treatment.

Patients will be followed for one month after the elective surgery.

Inclusion Criteria:

• • Patients must be mentally capable of understanding the information given.

  • Patients must give written informed consent.
  • Histologically verified adenocarcinoma of the rectum or sigmoid colon.
  • Tumor described as passable at index endoscopy.
  • Men or women aged at least 18 years.
  • Case reviewed by MDT (surgery, radiology, oncology). Case considered curable with standard surgical resection.
  • ASA class I-II (Classification of the American Society of Anesthesiology)

Exclusion Criteria:

• • Uncorrectable coagulation disorder.

  • Highly inflamed gastrointestinal tissue which is ulcerated and bleeding
  • Patients with ICD or pacemaker units.
  • Ongoing immunosuppressive treatment.
  • Patients with concomitant use of phenytoin.
  • Concurrent treatment with an investigational medicinal product.
  • Patients with any other clinical condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study or unable to comply with the study recruitments.
  • Advanced tumor stages, clinical UICC stage IV.
  • Indication for neoadjuvant chemoradiation or chemotherapy prior to surgery
  • Acute surgical resection.
  • Pregnancy