The frightening truth is that cancer can march unexpectedly into your life, affecting you directly or indirectly by striking someone you love, and colorectal cancer is no different. This year, an estimated 150,000 people in the United States will be diagnosed with colorectal cancer and more than 57,000 of them will die from it.

Colorectal cancer is the number two cause of cancer-related deaths among men and women combined. These statistics are a grim reminder of a fact that most people would rather ignore: Cancers of the colon and rectum are relatively common-and can be deadly.

But the good news-no, the great news-is that when found in its earliest stage, colorectal cancer can be cured fully more than 90 percent of the time! That said, I wish the story concluded there, but unhappily, we rarely find cancer in this early, curable stage, because not enough people are being screened for it.

A survey from the Harvard Report on Cancer Prevention shows that as many as 80 percent of Americans are not following the proper screening recommendations. Admittedly, many people shrink from the idea of colorectal cancer screening tests such as a colonoscopy because they are afraid of the preparation and procedure. More alarmingly, many health care practitioners simply are not telling their patients to get the recommended tests! Too few people understand that failing to undergo these tests means missing the chance to have potentially precancerous growths called polyps removed and facing a poor long-term outcome in the event that cancer is found in its later stages.

Colorectal cancer is in part a genetic disease, but one that is influenced greatly by your lifestyle-what you eat, whether you smoke, how active you are, how often you undergo routine screening, and, in general, how you live your life, day in and day out-all issues I will discuss in this book. As doctors, we now believe that, despite the role of genetics, almost all colorectal cancers can be prevented through lifestyle changes and regular screening. Just think: You can beat this disease with the right medical decisions and positive living.

A JOURNEY THROUGH YOUR DIGESTIVE SYSTEM

So that you can better understand the nature of colorectal cancer and how it affects your body, an important first step is to learn more about the fascinating inner workings of your digestive system. I'll run through an anatomy lesson with you, explaining key processes up front so that you can get comfortable with the terms I will be using throughout the book. For starters, let's follow a meal-say, a tuna salad sandwich-as it winds its way from your mouth down the twenty-five-foot tunnel commonly known as your digestive tract.

The Mouth

That sandwich you've just had for lunch begins its digestion in your mouth, where it is chewed and broken down by chemicals (enzymes) in your saliva into more absorbable forms. The carbohydrate in the bread, the protein in the tuna, and the fat in the mayonnaise each has its own set of digestive enzymes that go to work at various stages of digestion. An enzyme in your saliva, for example, begins the digestion of carbohydrates into simple sugars.

The Esophagus

Once a few bites of your sandwich have been chewed, moistened, and broken down, you swallow it-a process that involves many muscles working in sync to move the food down your esophagus (food pipe) into your stomach.

When your food arrives at the lower end of the esophagus, there is a valve, one of many "gates" that open and close, controlling entry to each digestive organ along the way. These valves are called sphincters.

They keep food and other material from passing backward into places where they shouldn't go.

Beginning in the esophagus, food moves smoothly through your entire digestive tract via a process called peristalsis, a coordinated, rhythmic wave of muscular contraction that travels in a single direction. Peristalsis works independently of gravity. You could eat while standing on your head, for instance, and food would still move from your esophagus to your stomach and through your system.

The Stomach

Your stomach stores the food material for hours and starts churning it into a more liquid form called chyme. Enzymes continue their work of breaking down the tuna salad sandwich. The digestion of protein occurs in your stomach, with proteins being chopped into microscopic fragments called amino acids. Protein can also be digested elsewhere in the digestive system, so even if you had your entire stomach removed, you could still digest food.

Another interesting aspect of the stomach is its production of hydrochloric acid. This acid is so corrosive that it can eat its way through metal. Fortunately, the inner lining of your stomach has a protective layer of mucus, or the acid would burn right through your stomach wall. Sometimes, acid can cause diseases such as ulcers and gastroesophageal reflux disease (GERD), but these are treatable with medications designed to block excessive acid production.

Hydrochloric acid is there for a reason: It activates some digestive enzymes in the stomach and it sterilizes the food you eat. Sterilizing food may not be such a big deal today because the food we eat is fairly clean and often cooked. It was a huge advantage ages ago, however, when early humans ingested bug-infested tree bark and rotting dead animals. Thank goodness for the invention of refrigeration and the supermarket! If you are taking medications to reduce stomach acid, don't worry. Our food supply is so clean and the digestion of nutrients is so repetitive in the gastrointestinal system that even complete acid suppression is well tolerated by the body. But back to that tuna salad sandwich: In its now partially digested form, it will usually sit in your stomach for two to four hours.

The Small Intestine

Your stomach empties the now liquefied sandwich into your small intestine via a sphincter known as the pyloric valve, which prevents the passage of partially digested food until it has been properly processed by your stomach. Made up of three segments-the duodenum, jejunum, and ileum-your small intestine is roughly twenty-one feet in length and coiled loosely in the part of your body commonly called the abdomen. When my patients tell me that they feel food and gas moving in their "stomach," what they are usually sensing is the movement of their small intestine as it digests food. In the small intestine, food is further broken down, and the jejunum and ileum are primarily responsible for absorbing the nutrients so they can be used to support the health and energy needs of your body. The lining of your small intestine is filled with closely packed, fingerlike projections called villi that greatly increase the amount of surface area available for absorbing nutrients. If all of these villi were spread out flat, their surface area would span the length of a tennis court, or about two hundred square feet. Incidentally, cancer is extremely rare in the small intestine.

Other Digestive Organs

Other digestive organs are involved in digestion. One is your pancreas, a flask-shaped organ situated just behind your stomach, toward the back. Its job is to secrete digestive enzymes into the small intestine in order to break down protein, carbohydrates, and fats. Apart from its digestive function, your pancreas also produces two hormones, insulin and glucagon, that are released into the blood and together help regulate the normal rise and fall in blood sugar. All the absorbed nutrients from digestion eventually pass through your liver, the largest solid organ in your body. The carbohydrate from the bread of the tuna sandwich, for example, arrives there as simple sugars. The liver converts these sugars to glucose, your body's primary fuel. Any glucose not used for fuel is stored in your liver or in your muscles as a larger molecule known as glycogen. The liver can also turn protein and fat into glucose if your body requires additional energy sources.

Among its many other functions, your liver also manufactures and secretes bile. Bile is a greenish liquid containing bile salts that emulsify, or break up, dietary fat so that it can be further broken down by enzymes.

Situated just under the liver is a pear-shaped organ known as the gallbladder. Its job is to receive bile from the liver and store it. During a meal, your gallbladder contracts and squirts bile into your duodenum through a tube called the common bile duct.

The Colon

Once the nutrients have been absorbed by your small intestine and processed by your liver, what is left of that tuna salad sandwich moves on by peristalsis to your colon, a muscular tube between four and six feet in length. The colon connects your small intestine to the rectum, the last part of the digestive tract. By the time the sandwich reaches your colon, the remaining material consists of undigested food particles (such as fiber), water, and secretions from your small intestine.

At the origin of the colon is a small pouch named the cecum, which includes an opening into a tiny nonfunctional tube called the appendix. This region is located in the lower right part of the abdomen and is also the site where the small intestine joins the colon. Anatomically, the colon is made up of four sections: the ascending (right) colon; the transverse (across) colon, which hangs like a necklace down to as low as your belly button; the descending (left) colon, which moves down the left side toward your pelvic area; and the sigmoid colon (so named for its S shape, derived from the Greek letter S, sigma). Cancer can develop in any of these four sections, as well as in your rectum.

Your colon is constructed of four layers of tissue. The innermost layer, the mucosa, is smooth, thin, and has no villi. It has direct contact with the material that passes through the colon. The cells of the mucosa are in a constant state of replenishment, dying, sloughing off, and being replaced by new cells about every four to six days. Underneath the mucosa is the submucosa, a layer of tissue that provides support for the mucosa. The submucosa also harbors the white blood cells (lymphocytes, monocytes, and neutrophils) that keep bacteria from the colon out of the bloodstream. The third layer is the muscularis propria, made up of muscle cells that assist in movement.

Finally, the fourth and outermost layer is the serosa, which provides added strength to the colon and serves as a protective barrier.

Sometimes the term colon is used interchangeably with large intestine. I dislike using the term large intestine because the small intestine is actually much longer than the colon. Therefore, so as not to confuse matters, I will use the term colon rather than large intestine, although these terms do refer to the same organ. The term bowel generally refers to any part of the intestine, large or small.

The primary duties of the colon are to absorb water and electrolytes, such as sodium and potassium, from the intestinal material and to compact solid waste so that it can be eliminated from your body. Think of the colon as a large "dryer" removing the water from the wet material left by the small intestine. As water is extracted in the colon, the material becomes more solid. In this state, it is called stool or feces. Stool moves upward from the cecum into the ascending colon, across the abdomen in the transverse colon, and then down the left side of your abdomen in the descending and sigmoid colons, where it is stored until being emptied into the rectum, usually once or twice a day.

Your colon also harbors an enormous colony of bacteria. When you hear about bacteria, it often brings to mind all those TV commercials showing us how to rid ourselves and our environment of these nasty bugs. Cleanliness seems to be forever equated with being germ-free. This is not an accurate depiction, however. There are, of course, pathogenic (disease-causing) bacteria in our environment, but most of the bacteria that we encounter are friendly and actually assist in the functioning of our digestion. Scientists theorize that the energy factory within our cells (the mitochondria) were at one time bacteria that joined our cells during an evolutionary process to form a mutually beneficial relationship. The reasoning behind this theory is that mitochondria have a DNA that is more similar to bacteria than it is to human DNA. So bacteria shouldn't always be stereotyped as being the bad guys; many are our friends.

Here is another interesting fact: By numbers alone, there are more bacteria in and on each of us than there are human cells in our bodies. In some ways, we are more bacteria than human! The helpful bacteria in the body, known as the normal flora, promote health and immunity in a variety of ways. First of all, they help stimulate the immune system's production of disease-fighting white blood cells. Second, they form a protective barrier in order to keep levels of bad bacteria from attaching to the colon walls and being absorbed. Third, they produce certain types of acid that discourage harmful organisms such as yeast from proliferating. Fourth, some normal flora synthesize certain B vitamins for proper metabolism, as well as vitamin K, which is essential to normal blood clotting. Finally, these bacteria help change fecal matter into a form that can be properly eliminated.

The presence of these friendly bacteria makes your colon an important organ of immunity. There is a vast interplay between the white blood cells in the intestine and the normal flora. Without these health-promoting bacteria in your colon, your body is less capable of functioning normally and fighting off disease.

As a whole, the digestive tract is the largest immune organ inside your body. Think about it. When we eat, we ingest foreign material that is loaded with environmental bacteria. The small intestines have to keep the bacteria out of the body, while absorbing the nutrients. Moreover, the intestines must decide if the ingested bacteria is safe or disease producing. As we discuss the specifics of colorectal cancer later in this book, the concept of the digestive tract, specifically the small intestine and colon, as an immune organ becomes important.

The Rectum

Although most people are usually too embarrassed to talk about the rectum, it is actually a vital part of the gastrointestinal tractreally. You may have heard a story about a debate among the body's organs as to which was the most important. When the rectum boldly asserted its importance, other organs like the brain and heart responded with derisive laughter. The rectum became so upset that it decided to shut down for a while and show the other body parts just how important it was. So the rectum closed up shop, and it wasn't long before the brain became foggy, the heart started beating faster, and the stomach felt queasy. Finally they all couldn't take it any longer and declared unanimously that the rectum was the most important part of the body.

If you have ever experienced a "work stoppage" of your rectum, you'll appreciate the truth of this story. There can be a great deal of abdominal discomfort and cramping if your rectum is not performing its job of storing and evacuating stool from your colon. Understanding the anatomy of both the colon and rectum is essential because colorectal cancer can occur in any part of these two organs. Further, the location of the disease plays a role in the type of treatment that is required.

The Anus

The rectum works in concert with the anus, located at the very end of the digestive tract. There, anal sphincter muscles block the movement of stool and prevent it from coming out when it is not supposed to. Together, the rectum and the anus expel stool. The pressure of the stool in the rectum stimulates movement. As a result, the rectal muscles contract, and the anal sphincter relaxes. Provided you're ready and in a bathroom, the anal sphincter relaxes under voluntary control and the stool is pushed out of your body. If you must "hold it" when the urge occurs, the anus remains closed until you can find a bathroom.

The time it takes for that tuna salad sandwich to enter at the mouth and exit at the anus is called transit time. If you eat a healthy diet, with plenty of water and fiber, your transit time should be just over a day.

THE FIVE DEADLIEST MYTHS ABOUT COLORECTAL CANCER

Now that you have a basic understanding of how your gastrointestinal tract works when it's healthy, I'd like to take our journey a step further by explaining some common myths about colorectal cancer. Don't let these myths get in your way of having regular screening tests and taking other measures to prevent colorectal cancer.

Myth 1: Only Old People Get It; Young People Don't

Here we start with a myth that is scary in its ramifications. Statistically, the incidence of colorectal cancer does begin to rise sharply as you get older, but even young adults in their twenties can get colorectal cancer. It is estimated that nearly 7 percent of colorectal cancer cases occur in people younger than age fifty. Consider the story of Molly McMaster, an ice-skating teacher and hockey coach in Colorado who was diagnosed with colon cancer in 1999 after enduring months of constipation and abdominal pain that resulted in so many days off from work that she was fired from her job. Molly headed to her hometown of Glenn Falls, New York, where she had emergency surgery that removed the cancer and twenty-five inches of her colon. Determined to create meaning out of her experience, Molly skated across the country, from Glenn Falls to Greeley, Colorado, a seventy-one-day, two-thousand-mile trip that ended in July 2000 in order to raise money and awareness for colorectal cancer. Molly's most recent educational creation is an amazing forty-foot crawl-through "Colossal Colon" that has been touring the United States. When the Colossal Colon came to visit New York City, I had the privilege of working with Molly and the Cancer Research and Prevention Foundation, and let me tell you, this lovely young vibrant woman is certainly not the person you would expect to have colon cancer. You see, when Molly was diagnosed with this disease, she was only twenty-three years old.

The story of Jay Monahan I shared with you in the Introduction should be another loud wake-up call that colorectal cancer does indeed strike the young. And it can strike a second time. Young people who have already had colorectal cancer, particularly those younger then forty, have a higher risk for getting colorectal cancer a second time than do people in older age groups. So please don't kid yourself. Although it does occur more frequently in people fifty and older, younger people can also succumb to colorectal cancer. And as you will hear me say again and again throughout this book: Caught in its earliest stages, colorectal cancer is curable more than 90 percent of the time.

Myth 2: Colorectal Cancer Is a Man's Disease

Don't ever believe this, not for one second! Although certain diseases occur more frequently in men than in women (or vice versa) colorectal cancer is not one of them. The truth of the matter is that colorectal cancer is an equal opportunity disease, striking both men and women with similar frequency.

For my women readers: Believing that colorectal cancer is a man's disease can be dangerous. Please be as aware of colorecal cancer as you are of breast or cervical cancer-add colorectal cancer screening to your list of must-have tests, right there with your mammogram and Pap test.

Myth 3: No One in My Family Ever Had Colorectal Cancer, so I'm Not at Risk

So many people believe this myth that it is sad, really sad. It is true that people with a strong family history of colorectal cancer are at increased risk for this disease. However, please understand that for nearly 80 percent of all people who get colorectal cancer, the disease does not run in the family. But let's forget statistics for a moment and talk about real life. In my fifteen years of practicing medicine, I have seen far too many patients with no family history of the disease who sadly found themselves with invasive colorectal cancer.

Truthfully, most of these people never had a screening test. They believed they just didn't need it or were never told about it because colorectal cancer didn't run in their family. I say this not to point a finger, but instead to hold your hand and reassure you that this disease is highly treatable and highly curable when caught in its earliest stages.

Myth 4: I Don't Need to Worry About Colorectal Cancer, I Feel Fine

This is the worst myth of them all. What do you think is the most common symptom of early colorectal cancer? Did you say blood in the stool or perhaps constipation? Well, this is actually a trick question because there are often no symptoms at all. People who have early colorectal cancer feel just fine. Only when the cancer grows does it cause symptoms. We believe that in average-risk individuals all colorectal cancers begin as a polyp that transforms over the course of years into cancer. Early on, when the cancer is small, it is painless and symptom free. The good news is that when a symptom-free person gets screened, even the worst scenario of finding a small cancer frequently results in a cure. The bottom line is not to wait for symptoms, but to get screened when you are feeling well.

Myth 5: Colorectal Cancer Always Starts with Blood in the Stool

This myth is based in some reality but it is dangerous because the sight of rectal blood often causes immediate fear. Most of the time, rectal bleeding is caused by hemorrhoidal swelling and inflammation. Yes, colorectal cancers can bleed, however, the amount of blood lost in the stool may be microscopic and not visible to the naked eye. In fact, bleeding may not occur at all. However, if a cancer or large polyp does bleed, this could appear as blood in the stool.

Frequently, the bleeding can be so subtle that the only symptom is fatigue from mild iron deficiency anemia (low blood count). Anemia can only be detected by a blood test known as a complete blood count (CBC) that determines the amount of red blood cells (hemoglobin and hematocrit values).

Blood in the stool is only one of the many symptoms that larger colorectal cancers can create. Remember, the earliest and smallest colorectal cancers are completely silent (see myth 4). Larger cancers can cause the signs and symptoms listed in the sidebar below. The changes in bowel habits occur because the cancer begins to narrow the inside of the colon, making it difficult for stool to pass. This is the reason a person may develop constipation, bloating, cramping, thinner or looser stool, or incomplete evacuation. In more advanced colorectal cancer, loss of appetite and/or unexplained weight loss can be noticed. These symptoms may occur from chemicals released by the cancer into the bloodstream as it grows and spreads (metastasizes) throughout the body. So, if you have any of the signs or symptoms of colorectal cancer listed below, it is very important that you see a doctor.

Don't let any of these myths stand in the way of possibly saving your life someday. Please don't.

Checklist of Signs and Symptoms of Colorectal Cancer If you're like most people, you may be uncomfortable talking about your intestinal functions. You've got to change your thinking. If you're not the one to tell your doctor about unusual symptoms-such as your stools changing shape-he or she will never know and sometimes may not even ask! Here's an overview of what to look for. Don't get frightened. Most of these symptoms are common and unrelated to cancer. However, let your doctor be the judge, not you:

• Change in bowel habits, including new and persistent loose stools; new or unusual constipation; uncomfortable bowel movements; pencil-thin stools; stools that appear more narrow than usual; and the feeling of incomplete emptying of the bowels.

• New abdominal discomfort such as gas, pain, bloating, cramping, or fullness.

• Bleeding (bright red or very dark blood in the stool).

• Constant fatigue.

• Unexplained weight loss.

• Unexplained iron deficiency.

• Unexplained anemia.