What is Colorectal Cancer?
Colorectal cancer (CRC) is a malignant neoplasm arising from the mucosa of the large intestine (colon) or rectum. It is the third most frequently diagnosed cancer and the second leading cause of cancer-related death worldwide. In Turkey, approximately 15,000 new cases are diagnosed annually.
The vast majority of colorectal cancers develop from adenomatous polyps through a well-characterized adenoma–carcinoma sequence spanning 5–15 years. This prolonged pre-malignant phase provides a critical window for detection and prevention through regular colonoscopic surveillance.
📌 Key fact: Five-year survival exceeds 90% when colorectal cancer is detected at Stage I. Regular colonoscopy is the single most effective intervention — it can prevent cancer by removing polyps before malignant transformation.
Risk Factors
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Genetic Predisposition
A first-degree relative with CRC or advanced adenomas doubles or triples individual risk. Hereditary syndromes — Lynch syndrome and FAP — confer substantially higher lifetime risk and require dedicated surveillance protocols.
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Dietary Factors
High consumption of red and processed meat, low dietary fiber intake, and a Western dietary pattern are independently associated with increased CRC risk.
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Inflammatory Bowel Disease
Long-standing ulcerative colitis and Crohn's colitis significantly increase CRC risk. Surveillance colonoscopy intervals are shortened in these patients.
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Lifestyle Factors
Cigarette smoking, excessive alcohol consumption, obesity, and physical inactivity are independent modifiable risk factors. Regular physical activity measurably reduces CRC incidence.
Symptoms & Warning Signs
⚠️ Emergency Presentation
Sudden severe abdominal pain, signs of complete bowel obstruction (absence of flatus and stool, marked abdominal distension), or large-volume rectal hemorrhage require immediate emergency department evaluation.
Early-stage colorectal cancer is characteristically asymptomatic, underscoring the importance of screening. Symptoms that develop with advanced disease include:
- Hematochezia (bright red rectal bleeding) or melena (dark, tarry stool)
- Persistent change in bowel habits: chronic diarrhea, constipation, or alternating pattern
- Pencil-thin stools — a classic sign of left-sided colon cancer
- Abdominal pain, cramping, bloating, and excess flatulence
- Unexplained, involuntary weight loss
- Persistent fatigue — often due to iron-deficiency anemia from occult bleeding
- Sensation of incomplete rectal evacuation (tenesmus)
Diagnosis & Staging
Diagnosis is established by colonoscopy with biopsy. Staging requires CT of the chest, abdomen and pelvis; MRI for rectal cancer; and molecular profiling (RAS, BRAF, MSI/MMR) to guide systemic therapy selection.
STAGE I
Confined to bowel wall
~90%
STAGE II
Through wall, node-negative
70–85%
STAGE III
Regional lymph node involvement
40–70%
STAGE IV
Distant metastases
10–20%
Survival data are based on the SEER database. Individual outcomes depend on tumor biology, patient performance status, and the experience of the treating surgical team.
Treatment
Multidisciplinary oncology board review is essential in colorectal cancer management. Prof. Dr. Hakan Yanar works in close collaboration with medical oncology and radiation oncology teams to develop an individualized treatment plan for each patient.
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Laparoscopic Colectomy — Current Standard of Care
Standard of Care
2–4 hrsOperating time
3–5 daysHospital stay
2–3 weeksReturn to work
≥12 nodesLymphadenectomy
Laparoscopic colectomy uses 3–5 small incisions (0.5–1.2 cm) to resect the tumor-bearing bowel segment with adequate oncological margins and complete mesocolic excision, including regional lymphadenectomy of at least 12 lymph nodes. Randomized controlled trials confirm oncological equivalence to open surgery.
Compared with open colectomy, the laparoscopic approach results in significantly less postoperative pain, shorter hospital stay (3–5 days), lower wound infection rates, and faster return to normal activity — without compromising cancer outcomes.
- Oncological outcomes equivalent to open surgery
- 60–70% reduction in postoperative pain
- Earlier return of bowel function
- Lower incisional hernia risk
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Robotic Surgery — Precision in the Pelvis
Rectal Cancer
3D HDVisualization
Tremor-freeInstrument movement
ShorterConversion rate
BetterNerve preservation
The da Vinci robotic platform provides three-dimensional high-definition visualization and tremor-filtered articulated instrumentation, offering superior dexterity in the narrow confines of the pelvis. This is particularly advantageous for total mesorectal excision (TME) in rectal cancer — the critical oncological procedure for local disease control.
Robotic TME facilitates autonomic nerve preservation (reducing risks of urinary and sexual dysfunction) and sphincter-sparing resection in mid and low rectal cancers. Prof. Dr. Hakan Yanar holds robotic surgery certification.
- Enhanced dexterity in confined pelvic space
- Superior autonomic nerve preservation
- Lower conversion-to-open rate than standard laparoscopy
- Certified robotic surgeon
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HIPEC — For Peritoneal Disease
Peritoneal Metastases
CRS+HIPECCombined procedure
41–43°CChemotherapy temp.
60–90 minPerfusion duration
Selected casesCurative intent
In patients with peritoneal metastases from colorectal cancer, cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) offers curative-intent treatment. The heated chemotherapy solution (41–43°C) is circulated through the abdominal cavity for 60–90 minutes following complete cytoreduction.
Patient selection is critical — ideal candidates have limited peritoneal disease (low Peritoneal Cancer Index) and good performance status. Prof. Dr. Hakan Yanar is HIPEC-certified and one of the few surgeons in Istanbul performing this procedure.
- Curative-intent option for selected peritoneal metastases
- Significantly prolongs survival vs. systemic chemotherapy alone
- HIPEC-certified surgeon in Istanbul
- Multidisciplinary patient selection
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Neoadjuvant Chemoradiotherapy — Rectal Cancer
Locally Advanced Rectal Cancer
5–6 weeksCRT duration
6–8 weeksInterval to surgery
15–30%pCR rate
↓ RecurrenceLocal control
Preoperative (neoadjuvant) chemoradiotherapy is the international standard of care for locally advanced mid and low rectal cancers. It reduces tumor volume, improves sphincter preservation rates, and lowers the risk of local recurrence. A pathological complete response (pCR) is achieved in 15–30% of patients.
In patients achieving pCR, a non-operative 'watch-and-wait' approach may be considered by the multidisciplinary team. Adjuvant chemotherapy (FOLFOX or CAPOX) for 6 months is recommended for Stage III disease following curative resection.
- Enables sphincter preservation in mid/low rectal cancers
- Reduces local recurrence to <10%
- pCR enables watch-and-wait in selected patients
- FOLFOX/CAPOX adjuvant chemotherapy for Stage III
Postoperative Recovery
Following laparoscopic colectomy, patients are typically discharged within 3–5 days. The Enhanced Recovery After Surgery (ERAS) protocol minimizes postoperative pain, nausea, and length of hospital stay. Oral intake is resumed within 24–48 hours. Most patients return to office work within 2–3 weeks and full physical activity within 3–4 weeks.
Surveillance after curative-intent surgery includes colonoscopy and CT at 3–6-month intervals in year one, then annually for 5 years, in accordance with international guidelines.
Colorectal Cancer Surgery in Istanbul
Prof. Dr. Hakan Yanar is an oncological surgeon with over 50 international peer-reviewed publications in gastrointestinal and colorectal cancer surgery, practicing at Istanbul University Faculty of Medicine and Liv Hospital Ulus. He offers consultations in English, French, and Russian for international patients, with full medical coordination support.
Sık Sorulan Sorular
What is colorectal cancer?
Colorectal cancer (CRC) is a malignant tumor arising from the epithelial lining of the colon or rectum. It is the third most common cancer worldwide and develops predominantly from adenomatous polyps over a period of 5–15 years, making regular colonoscopic surveillance highly effective for prevention.
What are the symptoms of colon cancer?
Early-stage CRC is often asymptomatic. Advanced disease presents with altered bowel habits (diarrhea, constipation, or alternating pattern), hematochezia or melena, pencil-thin stools, unexplained weight loss, fatigue from iron-deficiency anemia, and a sensation of incomplete evacuation.
How is colorectal cancer diagnosed?
Colonoscopy with biopsy is the gold standard. Staging is completed with CT of the chest, abdomen and pelvis; MRI for rectal cancer (to assess mesorectal fascia involvement); PET-CT when indicated; and molecular testing (RAS, BRAF, MSI/MMR status) to guide systemic therapy.
What is laparoscopic colon resection?
Laparoscopic colectomy uses 3–5 small incisions (0.5–1.2 cm) to resect the tumor-bearing bowel segment with adequate margins and regional lymphadenectomy. Randomized trials confirm oncological equivalence to open surgery with superior short-term outcomes: less pain, shorter hospital stay, and faster recovery.
What is HIPEC and when is it used in colorectal cancer?
HIPEC (hyperthermic intraperitoneal chemotherapy) is administered simultaneously with cytoreductive surgery in selected patients with peritoneal metastases from colorectal cancer. Prof. Dr. Hakan Yanar holds HIPEC certification and is one of the few surgeons in Istanbul performing this procedure.
What is neoadjuvant chemoradiotherapy for rectal cancer?
Preoperative chemoradiotherapy (CRT) is the standard of care for locally advanced mid and low rectal cancers. It reduces tumor volume, improves sphincter preservation rates, and reduces local recurrence. Pathological complete response (pCR) occurs in 15–30% of patients, enabling a watch-and-wait approach in selected cases.
At what age should colorectal cancer screening begin?
Average-risk individuals should begin screening at age 45–50. Those with a first-degree relative with CRC or advanced polyps should start 10 years before the youngest affected relative's age of diagnosis. Hereditary syndromes (Lynch syndrome, FAP) require earlier and more frequent surveillance.
Is a permanent colostomy always required?
No. The vast majority of colon cancer resections are performed without a stoma. A temporary diverting stoma may be used for low rectal anastomoses; it is typically reversed within 3–6 months. Permanent colostomy is rarely required and is reserved for abdominoperineal resection in very low rectal cancers.
Book a Colorectal Cancer Consultation
Contact Prof. Dr. Hakan Yanar for evaluation and a personalized treatment plan in Istanbul.
