A
Adenocarcinoma — The most common histological type of rectal cancer, developing from the glandular cells of the rectal mucosa.
Adjuvant — Treatment given after surgery (chemotherapy or radiotherapy) to reduce the risk of recurrence.
Aflibercept — A biological drug used in colorectal cancer treatment. Blocks vascular endothelial growth factor (VEGF), inhibiting the formation of new blood vessels in the tumor. Given intravenously, usually combined with FOLFIRI.
Anastomosis — The surgical suture by which two ends of the intestine are reconnected after the tumor segment is removed.
APR (Abdominoperineal Resection) — Operation in which the rectum and anus are completely removed, requiring a permanent stoma.
B
Bevacizumab — Monoclonal antibody that binds to vascular endothelial growth factor (VEGF), preventing the formation of new blood vessels feeding the tumor. Used in metastatic colorectal cancer.
Biofeedback — A retraining technique for the anal sphincter muscles, used in LARS treatment, with visual guidance on a monitor.
Biopsy — Taking a tissue fragment from the tumor for microscopic examination (histopathology).
Brachytherapy — A type of internal radiotherapy in which radioactive material is placed directly inside or near the tumor. Can be used as an alternative to local surgery in selected rectal cancer cases.
BRAF (mutation) — A specific change in the BRAF gene, involved in cell growth. Present in 5-10% of colorectal cancers, associated with a more guarded prognosis.
C
CAPOX — Chemotherapy regimen with capecitabine and oxaliplatin.
CEA (Carcinoembryonic Antigen) — A blood tumor marker used to monitor colorectal cancer. Elevated levels may indicate recurrence.
Cetuximab — Anti-EGFR (epidermal growth factor receptor) monoclonal antibody, used in metastatic colorectal cancer. Only effective in tumors without a RAS mutation.
Checkpoint inhibitor — A type of immunotherapy that “releases the brakes” on the immune system, allowing it to attack tumor cells. Examples: pembrolizumab, nivolumab, dostarlimab. Preferred treatment for dMMR/MSI-H tumors.
Chemoradiotherapy — The combination of chemotherapy and radiotherapy given simultaneously, frequently used in locally advanced rectal cancer.
Colostomy — A stoma made from the colon (large intestine), usually on the left side of the abdomen.
CRM (Circumferential Resection Margin) — The distance between the tumor and the lateral edge of the surgical specimen. A positive CRM (less than 1 mm) indicates increased risk of recurrence.
CT (Computed Tomography) — An imaging investigation used to assess distant metastases.
ctDNA (circulating tumor DNA) — Small fragments of DNA released by tumor cells into the blood. ctDNA testing (liquid biopsy) can detect microscopic residual disease after surgery. Not yet standard of care, but under active research.
D
Dysplasia — Disordered organization of intestinal mucosa cells, considered a stage preceding cancer. Can occur in the context of inflammatory bowel disease.
dMMR (deficient Mismatch Repair) — Deficiency in the DNA repair system; dMMR tumors may respond to immunotherapy.
DPD deficiency (Dihydropyrimidine Dehydrogenase) — A hereditary condition in which the body cannot properly break down 5-FU/capecitabine. Patients with this deficiency may have severe reactions to chemotherapy and require testing before treatment.
E
EMVI (Extramural Vascular Invasion) — The presence of tumor cells in blood vessels outside the rectal wall, visible on MRI.
Encorafenib — A drug that blocks the BRAF protein. Used in combination with cetuximab or panitumumab for metastatic colorectal cancers with the BRAF V600E mutation.
ERAS (Enhanced Recovery After Surgery) — An evidence-based protocol for accelerated recovery after surgery.
ESD (Endoscopic Submucosal Dissection) — A minimally invasive procedure recommended for T1 tumors, removing the entire cancer through an endoscope. Often curative, without the need for abdominal surgery.
F
FAP (Familial Adenomatous Polyposis) — A hereditary syndrome caused by mutation of the FAP gene, which causes hundreds or thousands of polyps in the large intestine from a young age. Cancer can develop before age 40, requiring surgical removal of the large intestine.
Fluoropyrimidines — A class of chemotherapy drugs (5-FU, capecitabine) that form the backbone of colorectal cancer chemotherapy.
FOBT (Faecal Occult Blood Test) — A test that detects occult blood in stool; a screening method for colorectal cancer. Detects traces of blood invisible to the naked eye.
FOLFIRI — Chemotherapy regimen with 5-fluorouracil, leucovorin and irinotecan. 48-hour infusion, repeated every 2 weeks.
FOLFOX — Chemotherapy regimen with 5-fluorouracil, leucovorin and oxaliplatin. 48-hour infusion, repeated every 2 weeks.
FOLFOXIRI — A triple chemotherapy regimen with 5-fluorouracil, leucovorin, oxaliplatin and irinotecan. More toxic, but may extend survival in metastatic disease.
Fruquintinib (Fruzaqla) — Oral targeted therapy used in metastatic colorectal cancer after other therapeutic options have been exhausted.
Mesorectal fascia — The connective tissue envelope surrounding the mesorectum; the dissection plane in TME.
Anastomotic fistula — A postoperative complication in which the anastomosis (suture) fails, allowing intestinal contents to leak.
G
Gy (Gray) — Unit of measurement for radiation dose. Typical long-course schedule: 45-50.4 Gy; short-course: 25 Gy.
H
HER2 (amplification) — A biomarker present in some metastatic colorectal cancers. Tumors with HER2 amplification (without RAS/BRAF mutations) can be treated with anti-HER2 targeted therapies (trastuzumab + pertuzumab).
I
Ileostomy — A stoma made from the small intestine (ileum), usually temporary, to protect the anastomosis.
Immunotherapy — Treatment that stimulates the patient’s immune system to recognize and destroy tumor cells. Preferred treatment for dMMR/MSI-H tumors. Recommended agents (NCCN 2025): pembrolizumab, nivolumab, dostarlimab, cemiplimab, retifanlimab, toripalimab, tislelizumab.
L
LAR (Low Anterior Resection) — Operation for upper and middle rectal tumors, with preservation of the anal sphincter.
LARS (Low Anterior Resection Syndrome) — A set of functional symptoms (urgency, frequency, incontinence) that occur after LAR.
Leucovorin (LV) — Also known as folinic acid; a drug given together with 5-FU to increase its effectiveness. The 5-FU/LV combination is the backbone of colorectal cancer chemotherapy.
Lynch syndrome — Hereditary syndrome (HNPCC) caused by mutations in DNA repair genes. Benign polyps transform into cancer faster (2-3 years instead of 10-15). Average age at diagnosis: 45 years. Also increases the risk of other cancer types.
M
MDT (Multidisciplinary Team) — The multidisciplinary oncology team that discusses each case: surgeon, oncologist, radiotherapist, radiologist, pathologist.
Mesorectum — The fatty tissue surrounding the rectum, containing lymph nodes and blood vessels. Its complete removal (TME) is essential.
MSI-H (Microsatellite Instability High) — A genetic feature of certain tumors that respond to immunotherapy.
N
Neoadjuvant — Treatment given before surgery (chemotherapy, radiotherapy, or their combination) to shrink the tumor.
NGS (Next-Generation Sequencing) — A technique that simultaneously tests multiple tumor biomarkers. Can identify rare mutations (NTRK, RET, KRAS G12C, POLE/POLD1) for which targeted treatments exist.
Peripheral neuropathy — Numbness, tingling and cold sensitivity in the hands and feet, a frequent side effect of oxaliplatin. May persist after treatment ends. Possible treatment: duloxetine, acupuncture.
P
Panitumumab — Anti-EGFR monoclonal antibody, similar to cetuximab. Used in metastatic colorectal cancer without RAS mutation.
PET (Positron Emission Tomography) — An imaging investigation that can highlight metastases and residual or recurrent tumors. Especially useful in combination with CT.
PIK3CA (mutation) — A mutation of the PIK3CA gene involved in cell growth. Tumors with this mutation respond better to aspirin given after surgery for recurrence prevention. Testing is recommended for stage II-III cancers.
pMMR (proficient Mismatch Repair) — A functional DNA repair system. pMMR (or MSS — microsatellite stable) tumors do not respond to immunotherapy and are treated with standard chemoradiotherapy.
Polypectomy — The procedure of removing a polyp, usually during a colonoscopy.
Precancerous lesion — A tissue change that is not cancer, but can evolve into cancer over time. Colorectal polyps are well-defined precancerous lesions.
Prehabilitation — A program of physical and nutritional preparation before surgery to optimize recovery.
R
RAS (mutations) — Mutations of the KRAS or NRAS genes, present in approximately 50% of metastatic colorectal cancers. The presence of a RAS mutation makes anti-EGFR therapies (cetuximab, panitumumab) ineffective. Testing is mandatory before starting these therapies.
Recurrence — The reappearance of cancer after treatment, either local (in the pelvis) or distant (metastases).
Regorafenib — An oral drug (multi-kinase inhibitor) used in metastatic colorectal cancer after all other therapeutic options have been exhausted.
Rectal MRI — Pelvic magnetic resonance imaging; an essential investigation for local staging of rectal cancer.
S
SBRT (Stereotactic Body Radiation Therapy) — A specialized type of external radiotherapy that delivers high doses of radiation with high precision. Used for unresectable liver or lung metastases, usually in 5 or fewer sessions.
SIRT/TARE (Selective Internal Radiation Therapy) — Radioembolization; an intra-arterial therapy that delivers radioactive spheres (Yttrium-90) directly into the blood vessels feeding the liver tumor. Stops the blood supply and irradiates the tumor simultaneously.
Sporadic — A term describing a cancer that occurs without a link to inherited genes. Approximately 80% of colorectal cancers are sporadic.
Stapler — A mechanical surgical instrument that creates the intestinal anastomosis (suture) with metal staples.
Stoma — A surgical opening created on the abdominal wall through which the intestine is brought to the surface, allowing stool to be collected in a bag.
Stoma nurse — A nurse specialized in the care and education of patients with a stoma.
Hand-foot syndrome — A side effect of 5-FU and capecitabine characterized by redness, pain and peeling of the skin on the palms and soles. Usually mild, but may require dose adjustment.
Vaginal stenosis — Narrowing and shortening of the vagina as a late effect of pelvic radiotherapy. Can be treated with vaginal dilator therapy.
T
TaTME (Transanal TME) — Total mesorectal excision via a transanal approach; a combined surgical technique, useful for low tumors.
TME (Total Mesorectal Excision) — The gold standard in rectal cancer surgery, developed by Prof. Bill Heald (1982).
TNM — Staging system: T (tumor), N (lymph nodes), M (metastases).
TNT (Total Neoadjuvant Therapy) — An approach in which all chemotherapy and radiotherapy are administered before surgery.
Trifluridine/tipiracil (Lonsurf) — Oral chemotherapy used in metastatic colorectal cancer after standard options have been exhausted. May be combined with bevacizumab.
V
VEGF (Vascular Endothelial Growth Factor) — A protein produced by tumor cells that stimulates the formation of new blood vessels. Bevacizumab and aflibercept block VEGF.
W
Watch & Wait — An observation strategy for patients with complete clinical response after chemoradiotherapy, avoiding surgery.