Colorectal cancer symptoms vary depending on the primary location of the tumor, and early clinical symptoms of colorectal cancer are often not obvious.
(Colorectal cancer symptoms 1) Symptoms of Right-Sided Colon Cancer:
Due to the wider lumen of the right colon and the liquid nature of its contents, intestinal obstruction is rare. Common symptoms include:
- In the early stages, right-sided abdominal pain and distension may occur after meals, sometimes resembling symptoms of chronic appendicitis or cholecystitis. Bloating may also occur, with intermittent attacks often following physical activity.
- A palpable mass in the right abdomen or cecum is a common initial symptom in 80% of right-sided colon cancers. As the tumor grows, local necrosis, bleeding, perforation, and subsequent infection may lead to persistent abdominal pain and tenderness. This may be accompanied by systemic toxic symptoms such as fever, anemia, weight loss, fatigue, and decreased appetite.
(Colorectal cancer symptoms 2) Symptoms of Left-Sided Colon Cancer:
Due to the narrow lumen of the colon and the semi-solid nature of stool within, primary tumors in this area are often infiltrative adenocarcinomas that grow in a circumferential manner. As the disease progresses, the tumor can lead to luminal narrowing and clinical manifestation of intestinal obstruction. Clinical symptoms include:
- Nausea and vomiting.
- Intermittent abdominal distension, abdominal pain, hyperactive bowel sounds, inability to pass stool or gas.
- Changes in bowel habits or the presence of a left-sided abdominal mass, indicating acute intestinal obstruction. Anemia may also be present. In 30% to 50% of cases, the tumor is only discovered during emergency surgery.
(3) Symptoms of Rectal Cancer:
More than 65% of colorectal cancers are rectal cancers. In the early stages, when rectal cancer forms small nodules in the mucosal layer, there are often no noticeable symptoms. The presence of the tumor can only be detected by a physician during a rectal examination. As the tumor grows and surface ulceration and infection occur, irritating symptoms may appear. Common symptoms include:
- Changes in bowel habits and stool characteristics, such as increased frequency of bowel movements, mucus in the stool, bloody stool, and diarrhea. These symptoms become more prominent when the tumor infiltrates deeper and the infection becomes more severe.
- Anal pain, tenesmus (feeling of incomplete evacuation), constipation, and abdominal pain.
- Feeling of incomplete evacuation after bowel movements, anal incontinence, discharge, and foul-smelling pus and blood.
- Localized pain and difficulty sleeping.
- Anemia, symptoms of intestinal obstruction, and potential for significant bleeding.
(4) Late-stage Manifestations of Colorectal Cancer:
As colorectal cancer progresses to advanced stages, local infiltration can cause abdominal pain; perforation can lead to acute peritonitis and abdominal abscess; liver metastasis can cause hepatomegaly, jaundice, and ascites; lung metastasis can result in cough, dyspnea, and hemoptysis; brain metastasis can lead to coma; bone metastasis can cause bone pain and fractures, among others. Ultimately, it can lead to cachexia and systemic failure.
Colorectal cancer is a significant health concern in the United States, with data indicating that it is the third most common cancer diagnosed in both men and women. According to statistics, approximately 150,000 new cases of colorectal cancer are reported each year in the U.S. The disease is responsible for over 50,000 deaths annually, making it the second leading cause of cancer-related deaths. Risk factors for colorectal cancer include age, family history, lifestyle choices such as smoking and diet, as well as certain genetic conditions.
Screening for colorectal cancer is recommended for individuals over the age of 50, as early detection can greatly improve treatment outcomes. Treatment options for colorectal cancer may include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy, depending on the stage and characteristics of the cancer. Public health initiatives promoting awareness, screening, and healthy lifestyle choices are crucial in reducing the incidence and mortality rates associated with colorectal cancer in the United States.
