OVERVIEW

What is sigmoid colon cancer?

Sigmoid colon cancer is a type of colon cancer, specifically a malignant tumor occurring in the sigmoid colon.

In its early stages, sigmoid colon cancer often presents with no obvious symptoms and is easily overlooked. A small number of patients may experience mild abdominal pain, reduced food intake, or changes in bowel habits. In the mid-to-late stages, symptoms typically include persistent abdominal discomfort, abdominal pain and bloating, constipation, bloody stools, anemia, weight loss, and abdominal masses. Bowel obstruction is a common manifestation of advanced sigmoid colon cancer.

Is sigmoid colon cancer common?

Sigmoid colon cancer is relatively common. Colon cancer has a high incidence rate, ranking third among gastrointestinal tumors. Recent research data indicate that the incidence of sigmoid colon cancer in China has been steadily increasing and currently ranks among the top five malignant tumor diseases^[1].

SYMPTOMS

What are the common symptoms of early-stage sigmoid colon cancer?

Most patients with early-stage sigmoid colon cancer do not exhibit symptoms, and the condition is often detected through colonoscopy screening or fecal occult blood tests. Typical symptoms include bloody stools, abdominal pain, changes in bowel habits, and unexplained iron-deficiency anemia.

In early-stage sigmoid colon cancer, the tumor is usually small and confined to the mucosal or muscular layer, without invasion of surrounding lymph nodes, blood vessels, or nerves. Since the cancer causes minimal damage to the sigmoid colon tissue, early-stage patients may not show clinical symptoms.

Due to damage to the sigmoid colon mucosa by the cancerous tissue, local mucosal inflammation occurs, causing some sensitive patients to experience mild abdominal pain. Some patients may also experience loss of appetite due to mucosal inflammation, leading to reduced food intake.

As the tumor partially obstructs the sigmoid colon, patients may feel abdominal fullness after eating. This bloating usually improves with moderate exercise, making it easy for patients to overlook.

What are the types and stages of sigmoid colon cancer?

Classification of Sigmoid Colon Cancer

Based on disease progression, it can be divided into early-stage and advanced-stage types. Early-stage sigmoid colon cancer is further classified into four subtypes: flat, polypoid elevated, flat elevated, and flat elevated ulcerative. Advanced-stage sigmoid colon cancer is divided into three subtypes: mass-forming, ulcerative, and infiltrative.

Staging of Sigmoid Colon Cancer

Currently, the TNM staging system (an internationally recognized tumor staging system that evaluates the primary tumor, regional lymph node involvement, and distant metastasis to determine the stage) is used, categorizing the disease into stages 0, I, II, III, and IV^[1].

• Stage I: The tumor is confined to the submucosa or muscular layer, with no regional lymph node or distant metastasis.
• Stage II: The tumor penetrates the muscular layer or invades surrounding tissues of the sigmoid colon, with no regional lymph node or distant metastasis.
• Stage III: Regional lymph node metastasis is present, but there is no distant metastasis.
• Stage IV: Distant metastasis has occurred.

Additionally, based on pathological types, it is commonly classified as adenocarcinoma or mucinous carcinoma. Undifferentiated carcinoma, neuroendocrine tumors, stromal tumors, and lymphoma are relatively rare.

Which areas or organs can sigmoid colon cancer affect?

Sigmoid colon cancer can involve surrounding tissues of the sigmoid colon, as well as cause peritoneal metastasis and distant organ metastasis.

1. Involvement of surrounding tissues: The cancer spreads locally or via lymphatic pathways, leading to involvement of adjacent tissues such as the descending colon, mesentery, rectum, sigmoid colon lymph nodes, and mesenteric lymph nodes.
2. Peritoneal metastasis: This occurs when cancer cells shed into the abdominal cavity, leading to seeding metastasis (spread to other organs).
3. Distant organ metastasis: Sigmoid colon cancer can also spread hematogenously, commonly affecting the liver, lungs, ovaries, brain, and bones. It can also metastasize to distant lymph nodes, such as retroperitoneal or supraclavicular lymph nodes, via lymphatic pathways.

CAUSES

What are the causes of sigmoid colon cancer?

The exact cause of sigmoid colon cancer is unclear, but contributing factors may include poor lifestyle habits, disease-related factors, genetic predisposition, age, and other elements^[2].

1. Poor lifestyle habits: Excessive intake of fat and sugar, lack of dietary fiber, long-term smoking, alcohol abuse, and obesity can increase the risk of sigmoid colon cancer^[3].
2. Disease-related factors: Certain colon diseases, such as Crohn's disease or ulcerative colitis, may raise the incidence of sigmoid colon cancer. Additionally, patients with colon polyps face a higher risk of malignancy, especially if the polyps exhibit high-risk pathological features, are numerous, or large in size.
3. Genetic factors: Individuals with a family history of the disease, particularly first-degree relatives who have had colon cancer, are more likely to develop it—about four times higher than the general population—and may experience earlier onset^[2].
4. Age factor: The incidence generally increases with age, and individuals over 50 face a higher risk^[7].
5. Other factors: Patients who have undergone ureterosigmoidostomy have a significantly increased risk of sigmoid colon cancer.

Which groups are at high risk for sigmoid colon cancer?

High-risk groups include those with long-term high-fat, low-fiber diets, inflammatory or adenomatous intestinal diseases, or a family history of colorectal cancer^[2].

1. Long-term high-fat, low-fiber diet: This refers to excessive consumption of fatty meats, fried foods, animal liver, or seafood, coupled with insufficient intake of fresh fruits and vegetables. Such dietary habits elevate the risk.
2. Chronic ulcerative inflammation or neoplastic polyps in the sigmoid colon: These conditions carry a higher risk of malignant transformation.
3. Family history of colorectal tumors: Individuals with parents or siblings who have had colon cancer face an elevated risk.

Is sigmoid colon cancer hereditary?

Sigmoid colon cancer has a notable genetic predisposition. Individuals with a family history of colon cancer are more susceptible, with about 20% of cases linked to familial clustering. The most common hereditary form is Lynch syndrome (also known as hereditary nonpolyposis colorectal cancer)^[8].

Therefore, those with a family history, especially first-degree relatives diagnosed with colon cancer, should be considered high-risk and undergo annual screenings (e.g., colonoscopy) for early detection^[4].

DIAGNOSIS

Under what circumstances should patients with sigmoid colon cancer seek medical attention promptly?

1. When patients repeatedly experience symptoms such as bloody stools, changes in bowel habits, abdominal pain, bloating, constipation, weight loss, fever, and other clinical manifestations, they should be alert to the possibility of sigmoid colon cancer and seek standardized diagnosis and treatment at a hospital.

2. Patients with a history of colon cancer should seek regular medical check-ups. If symptoms such as abdominal pain and bloating worsen compared to before, they should be vigilant about cancer recurrence and seek medical attention promptly.

   Sigmoid colon cancer can also spread extensively through blood and lymphatic pathways, causing dysfunction in multiple organs and severe complications that threaten the patient's life. Patients should undergo regular examinations as advised by their doctors so that recurrence can be treated promptly and effectively.

Which departments should patients with sigmoid colon cancer visit?

Patients suspected of having sigmoid colon cancer can visit the general surgery or gastroenterology department. Some medical institutions have a proctology department. If diagnosed, patients can also visit the oncology department for treatment.

What tests are generally required for patients with sigmoid colon cancer?

Patients with sigmoid colon cancer generally need to undergo systematic physical examinations, laboratory tests, imaging studies, endoscopic examinations, and pathological examinations.

1. Systematic physical examination: Primarily focuses on abdominal examination, including inspection, palpation, percussion, and auscultation. The patient's overall condition, such as weight loss, pain, fever, and poor mental state, is also observed.
2. Laboratory tests: Include routine blood, urine, and stool tests, fecal occult blood tests, liver and kidney function tests, as well as tumor marker tests such as CEA, CA 724, and CA 19-9, usually conducted via blood tests.
3. Imaging studies: Include abdominal CT, abdominal MRI, and PET-CT scans to determine the size, location, and extent of the lesion.
4. Endoscopic examination: Mainly refers to colonoscopy, which can obtain tissue samples for subsequent pathological examination.
5. Pathological examination: The pathological results of sigmoid colon biopsy specimens are a critical indicator for clinically diagnosing sigmoid colon cancer.

What preparations should patients with sigmoid colon cancer make before seeking medical attention?

Before the visit, patients should rest, avoid strenuous exercise, quit smoking and alcohol, regulate emotions, and maintain good sleep.

Additionally, it is important to note that diagnosed patients should not take any medication without their doctor's approval to avoid interfering with the diagnosis and treatment.

If sigmoid colon cancer is suspected, what questions might the doctor ask during the visit?

During the visit, the doctor may ask the following questions. Patients can prepare in advance to help the doctor quickly assess the condition:

1. When did the symptoms start, and have they worsened over time?
2. How long have the symptoms persisted?
3. Is there a history of colon diseases or a family history of such conditions?
4. Have you visited other hospitals before? What tests were done, and what were the results?
5. Have you undergone any other treatments? What medications have you taken previously?

How can patients with sigmoid colon cancer quickly understand their condition?

During the visit, patients can ask the following questions to better grasp their condition and make informed decisions about treatment options:

1. What are the most likely factors contributing to my sigmoid colon cancer?
2. What stage is my disease currently in?
3. What additional tests are needed?
4. What treatment options are available? If there are multiple choices, what are their pros and cons?
5. If the recommended treatment is adopted, what complications or side effects might occur?
6. How often should follow-up visits be scheduled after treatment? Is recurrence likely?
7. What should I pay attention to in daily life after treatment?

TREATMENT

What are the treatment options for patients with sigmoid colon cancer?

Treatment options for patients with sigmoid colon cancer include surgical treatment, drug therapy, and local therapy^[2].

1. Surgical treatment. It remains one of the most important treatment methods. Radical resection and palliative resection are the two main approaches. Radical resection of the sigmoid colon cancer tumor is currently a key treatment that may offer a cure for patients.
2. Drug therapy. This includes antitumor drugs such as chemotherapy drugs, targeted therapy drugs, and immunotherapy drugs, as well as symptomatic supportive medications like pain relievers and nutritional supplements.
3. Local therapy. Includes endoscopic treatment and radiotherapy.

How is intestinal obstruction treated in patients with sigmoid colon cancer?

For sigmoid colon cancer patients with obstruction, treatment varies based on the severity of the obstruction and may include medical therapy, surgical relief of obstruction, placement of a feeding tube or stent, and antitumor therapy.

1. Medical therapy. Primarily involves drug treatment, fluid replacement, and gastrointestinal decompression to alleviate symptoms of intestinal obstruction.
2. Surgical relief of obstruction. Mainly includes procedures such as enterostomy, intestinal anastomosis, and adhesiolysis to remove the obstruction and address the underlying cause.
3. Placement of a feeding tube or stent. A nasogastric feeding tube may be inserted to deliver nutritional fluids directly into the body. Alternatively, a stent may be placed in the obstructed intestine to expand the passage and allow stool to pass.

Since obstruction in sigmoid colon cancer is often caused by cancer metastasis, antitumor therapy is also necessary to control the progression of the disease.

What are the commonly used drugs for patients with sigmoid colon cancer?

Commonly used drugs for sigmoid colon cancer patients include chemotherapy drugs, targeted therapy drugs, and immunotherapy drugs.

1. Chemotherapy drugs. Commonly used drugs include oxaliplatin, capecitabine, 5-fluorouracil, raltitrexed, tegafur-gimeracil-oteracil potassium capsules (S-1), irinotecan, and TAS-102 (trifluridine/tipiracil).
2. Targeted drugs. Clinically used options include cetuximab, bevacizumab, apatinib, regorafenib, fruquintinib, and anlotinib.
3. Immunotherapy drugs. Drugs such as nivolumab, camrelizumab, and pembrolizumab are generally used as first-line treatment for advanced sigmoid colon cancer patients or in combination with chemotherapy for later-line treatment.

What happens if sigmoid colon cancer patients do not receive treatment?

If left untreated, sigmoid colon cancer will grow and spread extensively throughout the body, causing patient suffering, reducing quality of life, and ultimately leading to death.

Without surgical, radiation, or chemotherapy treatments, the tumor will grow uncontrollably, obstructing the intestinal lumen and causing cancerous bowel obstruction, leading to symptoms such as abdominal pain, vomiting, and inability to defecate. Invasion of blood vessels may cause bleeding, resulting in anemia, dizziness, or shock. Metastasis to organs like the lungs or liver may cause coughing, chest pain, difficulty breathing, abdominal distension, and poor appetite, significantly reducing the patient's quality of life.

Furthermore, widespread metastasis of sigmoid colon cancer can lead to failure of vital organs such as the liver, heart, and lungs, ultimately resulting in death.

Is the cure rate high for sigmoid colon cancer patients with timely treatment?

The cure rate for sigmoid colon cancer patients with timely treatment depends on factors such as clinical stage and the malignancy of the pathological type.

Generally, the earlier the clinical stage and the lower the malignancy of the pathological type, the higher the cure rate.

For example, early-stage sigmoid colon cancer patients who undergo timely surgical resection often achieve clinical cure, with a high five-year survival rate.

For advanced-stage patients, the cure rate is generally lower. However, with prompt and aggressive antitumor therapy, patients who respond well to treatment may still achieve prolonged survival.

DIET & LIFESTYLE

What should sigmoid colon cancer patients pay attention to in daily life?

Sigmoid colon cancer patients should focus on dietary adjustments, moderate exercise, and maintaining good lifestyle habits.

1. Dietary adjustments. The occurrence of sigmoid colon cancer is closely related to a high-fat, low-fiber diet. Therefore, patients should increase their intake of fresh vegetables and fruits while reducing high-fat foods such as animal organs, fatty meats, fried foods, and preserved foods. Postoperative patients should follow the principle of eating smaller, more frequent meals.
2. Moderate exercise. Patients should engage in appropriate physical activities like jogging or walking to avoid obesity and reduce the risk of disease recurrence or metastasis.
3. Regular routine. Patients should develop healthy habits such as maintaining a regular schedule, avoiding overeating, staying up late, and refraining from smoking and drinking.

How should sigmoid colon cancer patients arrange their daily diet?

The dietary arrangements for sigmoid colon cancer patients include postoperative diet planning and daily dietary management.

For postoperative patients, if there is no gas or bowel movement within three days after surgery, they should avoid eating or drinking.

Once bowel function begins to recover (evidenced by gas or bowel movements), patients can start with small amounts of liquid food, gradually transitioning to semi-liquid and then solid foods. Once bowel function normalizes, they can resume a regular diet while maintaining smaller, more frequent meals.

In daily life, patients should:

• Limit intake of high-fat foods such as red meat, processed meats, sweets, fried foods, pickled foods, and animal organs.
• Avoid overly cold, spicy, or high-sugar foods.
• Increase consumption of fresh vegetables, fruits, and fiber-rich grains.

Do sigmoid colon cancer patients need psychological counseling?

Yes, psychological counseling is necessary for sigmoid colon cancer patients.

The disease can cause symptoms like abdominal pain and bloating, leading to distress and negative emotions such as anxiety, anger, fear, and depression. These emotions may result in resistance to treatment, hindering the progress of anti-cancer therapies. Psychological support helps patients build confidence and cooperate with treatment plans^[5].

Advanced-stage patients may experience severe pain, inability to eat, and extreme weight loss, increasing the risk of depression and suicidal tendencies. Counseling is crucial to maintaining their psychological balance.

How should sigmoid colon cancer patients exercise?

Patients should engage in aerobic exercises, gradually increasing intensity while avoiding excessive strain.

Based on individual fitness levels, patients can choose suitable aerobic activities like jogging, walking, swimming, or yoga, ensuring consistency.

Exercise intensity and duration should be increased progressively to prevent injuries or overexertion.

Moderate exercise helps prevent obesity, reduces disease progression risks, and enhances immunity.

Does chemotherapy and radiotherapy for sigmoid colon cancer affect sexual life?

Yes, these treatments may reduce libido and sexual satisfaction.

Side effects like nausea, vomiting, bloating, fatigue, and weakened immunity can lower sexual desire and performance.

Additionally, engaging in sexual activity during treatment may increase the risk of bleeding or infection due to low platelet or white blood cell counts, potentially disrupting treatment schedules and efficacy.

Does chemotherapy and radiotherapy for sigmoid colon cancer affect fertility?

Yes, these treatments can impact fertility, so contraception is advised during this period.

Radiotherapy may rarely reduce sperm production due to testicular exposure, requiring protective measures^[6].

Chemotherapy drugs like oxaliplatin and fluorouracil can damage reproductive cells, causing mutations or menstrual irregularities, including ovarian failure.

Therefore, patients should avoid sexual activity and use contraception strictly during treatment.

PREVENTION

How to prevent sigmoid colon cancer?

Clinical preventive measures for sigmoid colon cancer include dietary intervention, early cancer screening, and active prevention.

1. Dietary intervention. Measures include increasing the intake of foods high in vitamins and dietary fiber, such as fruits like strawberries and apples, and vegetables like broccoli, celery, and cabbage. Reduce the intake of high-fat foods, such as fried fish, fried meat, fatty meat, and animal organs.
2. Early cancer screening. This mainly refers to regular annual examinations such as colonoscopy, carcinoembryonic antigen (CEA), carbohydrate antigen 724 (CA724), and carbohydrate antigen 19-9 (CA19-9) for high-risk groups, particularly those with a family history of colorectal cancer.
3. Active prevention. For primary intestinal diseases, such as sigmoid colon polyps or chronic ulcerative sigmoid colitis, which are precancerous lesions, proper prevention and treatment can help reduce the incidence of sigmoid colon cancer to some extent.