Rectal cancer

What is rectal cancer (rectal carcinoma)?

The rectum is the last section of the large intestine. A malignant tumor that develops in this area is known as rectal cancer. Often, cancers of the colon are grouped together under the term colorectal carcinoma.

The colon is approximately 1.5 meters long and functions to thicken undigested food for it to be excreted in the stool. The last section is the rectum, the so-called continence organ, which allows stool to be passed through the anal canal in a regulated and controlled way with the help of various muscles. Around a third of colorectal cancers affect the rectum.

The cancer develops from mucosal cells, which multiply uncontrollably and invade surrounding tissue. Through infiltration of lymphatic or blood vessels, the cancer cells can then also form metastases in other organs.

In Germany, colorectal cancer is the second most common cause of cancer-related deaths in both men and women. The disease usually develops after the age of 50. With around 60,000 new cases per year, colorectal cancer is one of the most common diseases.

What are the causes for rectal cancer? 

Various factors contribute to the development of rectal cancer. In many cases, multiple factors combine to trigger the disease. Ultimately, cancer develops due to mutations in the genetic material of cells. These mutations alter the cells in such a way that the abnormal cells multiply independently of external influences.

Rectal cancer can generally be classified into three causative groups: those with familial cancer syndromes, individuals with chronic inflammatory bowel diseases that create a foundation for cancer development, and patients with no underlying conditions.

The last-mentioned group represents the largest proportion, comprising about 90% of cases. In this group, no predisposing preexisting conditions are known. However, many of these patients have risk factors that promote the onset of the disease. These include a diet high in fat and cholesterol with a large proportion of processed meat, obesity, smoking, and high alcohol consumption.

In about 5–10% of cases, rectal cancer develops in patients with defined familial cancer syndromes. The two most common are familial adenomatous polyposis coli (FAP) and hereditary non-polyposis colorectal cancer (HNPCC).

In FAP, a genetic mutation promotes the development of mucosal growths known as adenomas. These growths can become malignant and lead to rectal cancer. In HNPCC, there is also a mutation that promotes malignancy. In most cases, the carcinoma develops before the age of 50.

Approximately 1–2% of all colorectal cancers develop on the basis of chronic inflammatory bowel diseases, such as ulcerative colitis and Crohn's disease. These diseases involve intermittent or persistent inflammation in the mucosal lining of the intestine. This inflammatory process can lead to malignancy of the mucosal cells and, thus, to colorectal cancer.

What are the common symptoms?

The insidious nature of colorectal cancer is the common absence of specific symptoms, which means the disease is often only detected at an advanced stage.

Sudden changes in bowel movements can be a sign of rectal cancer. This includes, for example, diarrhea or constipation, bloody streaks, involuntary bowel movements with bloating or even “pencil stools”, in which the stool is very thin due to a narrowing of the bowel (stenosis).

In advanced stages, patients may also experience other symptoms like night sweats, weight loss and fever. Reduced efficiency, increased fatigue and non-specific abdominal pain may also accompany the condition.

In the late stages, rectal cancer can also lead to symptoms of bowel obstruction caused by progressive stenosis and narrowing of the bowel. The symptoms of this usually include pain, absolute stool retention and sometimes vomiting.

How is rectal cancer diagnosed?

The diagnostic process for rectal cancer always begins with a detailed medical history. This includes not only a thorough assessment of symptoms but also a comprehensive family history. A physical examination takes place following this.

A digital rectal examination (DRE) is performed as part of the physical examination. This involves the physician palpating the mucosa of the anal canal and rectum using a finger. The use of a lubricant minimizes discomfort for the patient. The main focus is on detecting palpable tumors, stenoses, or bleeding.

The gold standard for diagnosing colorectal cancer is colonoscopy. During this procedure, a specialized endoscope is inserted into the rectum, allowing for precise inspection of the intestinal mucosa via a camera. If suspicious areas are identified, biopsy samples can be taken using additional instruments. These samples are then sent to a laboratory for histopathological analysis, which allows for a definitive diagnosis.

To assess tumor spread and potential metastases in other organs, further imaging techniques are employed. These typically include an abdominal ultrasound, chest X-ray, and computed tomography (CT) scan.

For tumors located in the rectum, additional examinations may be conducted using a rigid rectoscope, which enables precise localization of the tumor. To rule out local tumor invasion into adjacent organs, gynecological or urological examinations may also be performed if indicated.

Although not primarily diagnostic, tumor markers in the blood may be measured for monitoring purposes. In the case of rectal cancer, the carcinoembryonic antigen (CEA) level is most commonly evaluated.

How is rectal cancer treated?

An individual treatment plan is prepared after a complete diagnosis has been made and is based on the stage of the disease and the patient's general state of health. The treatment consists primarily of three different pillars: surgical measures, chemotherapy and radiotherapy.

The primary focus is on removing the tumor as completely as possible. Tumors located in the lower two-thirds of the rectum are often initially treated with chemotherapy to reduce their size and preserve continence function as much as possible. If this is not successful, the creation of a colostomy (artificial bowel outlet) may be necessary.

Depending on the tumor stage and the presence of risk factors, surgical removal is often followed by chemotherapy and/or radiation therapy targeting the affected area.

If the cancer has already spread to other organs and formed metastases, a decision must first be made as to whether these can be surgically removed. If this is not feasible, systemic chemotherapy is usually administered. The goal of this treatment can either be to reduce the size of the metastases or to adopt a palliative approach.

Palliative therapy is considered when a complete cure is no longer deemed possible. The aim is to maintain or improve the patient’s quality of life. This form of therapy is typically used in cases of advanced tumors with extensive metastases.

What is the procedure for rectal cancer surgery?

In most cases, colorectal cancer can be treated surgically with the potential aim of curing the disease. Depending on the extent of the tumor or the spread of metastases, the surgery can be performed either as an open procedure or minimally invasively using laparoscopy (keyhole surgery).

During the operation, the surgeon first assesses the exact extent of the tumor to confirm whether it matches the findings from preoperative imaging. If there is any uncertainty, tissue samples may be taken and examined under a microscope during the procedure. This is done very cautiously to avoid spreading tumor cells.

Once the assessment is complete, the affected section of the bowel, along with the surrounding lymphatic drainage area, is removed. The focus here is on ensuring the tumor is excised with a sufficient safety margin and without damaging it.

After the tumor is removed, the surgeon will evaluate whether bowel continence can be preserved. The patient’s expected quality of life after the procedure plays a great role in this decision. If the surgery significantly affects the bowel structures, a colostomy (artificial bowel outlet) may be necessary.

A colostomy, or stoma, allows stool to exit through an opening in the abdominal wall into a specially designed pouch. The patient can empty this pouch independently.

Which doctors & clinics specialize in the treatment of rectal cancer? 

Rectal cancer, as with all cancers, is a significant turning point in the lives of those affected. Competent medical care is thus even more important. Specialists in gastroenterology and oncology specialize in the treatment of rectal cancer. In addition, specialists in visceral and general surgery and radiation oncology are involved in the treatment.

We have made it our goal to connect patients with suitable practitioners. We have therefore thoroughly reviewed and selected all the specialists listed here. They are all experts in their field and competent contacts for all questions relating to rectal cancer.

We also want to make it easier for you to contact certified colorectal cancer centers. These centers bring together specialists from various fields to provide all-round care for patients with colorectal cancer through interdisciplinary cooperation.

Schedule an initial consultation with our experts quickly and easily, and see for yourself their expertise and experience.