Connection between obesity and colorectal cancer differs between men and women

Researchers in Sweden reviewed thirty studies relating obesity (body mass index) to colon or rectal cancer in both men and women.  They found differences between risks for men and women and whether the cancer was located in the colon or the rectum.

Men who were overweight had a greater increase in their risk than women for both colon and rectal cancer.  For colon cancer, obesity increase men’s risk by 30 percent, but women only had an 12 percent increase.

For rectal cancer, obese men had a 12 percent greater risk, but there was no similar increased risk for women.

For both men and women larger waist size increased colon cancer risk.  Again the risk was greater for men.

Susanna C Larsson and Alicja Wolk from the Karolinska Institute in Stockholm concluded:

The association between obesity and colon and rectal cancer risk varies by sex and cancer site.

SOURCE:  Larsson et al, American Journal of Clinical Nutrition, Volume  86, Number 3, pages 556-565, September 2007

Posted by Kate Murphy on September 10th, 2007
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Low doses of irinotecan may not require genetic testing before treatment

Cancer patients who have a specific genetic type are at risk for serious — sometimes life-threatening — side effects when they are treated with Camptosar® (irinotecan).  The FDA-approved Camptosar label now calls for gene testing before beginning irinotecan treatment.

Previous studies have found about ten percent of patients will have a variation in the UGT1A1 gene that makes them particularly sensitive to irinotecan.

 However, researchers at the University of North Carolina reviewed nine studies in which irinotecan was given in high, medium, and low doses.  They found that although the genetic type UGT1A1*28/*28 increased risk of serious changes in blood counts at high and medium doses, at low doses side effects were similar in patients whether or not they had the special genotype.

Low doses of irinotecan (100–125 mg/m²) are commonly used for colorectal cancer treatment.

In a news release from the University of North Carolina,  Harold MacLeod, Pharm. D. said about the study’s implications,

Many institutions saw the FDA’s recommendation as a mandate to test all patients before treating them with irinotecan even though many clinicians didn’t think it was always necessary given that low doses of the drug weren’t causing problems

Our review showed that at low doses the drug is well tolerated and can be taken by most people. As the dosage increases, genetics become a larger factor in determining what side effects patients experience, and then testing becomes essential.

Richard M. Goldberg, MD added,

Having a genetic test available for a medicine is valuable, but so is knowing when to use that test.

There are so many treatment options for cancer patients that the more information we have about matching the right therapy to the patient, the better off we all are. Studies like this one give oncologists the tools needed to take better care of patients while avoiding tests and expenses that aren’t needed.

The study authors recommend that FDA labeling be changed to reflect the impact of irinotecan dose on side effects related to UGT1A1 genotype.

SOURCE: Hoskins et al, Journal of the National Cancer Institute, Volume 99, Number 17, 5 September 2007.

Posted by Kate Murphy on September 10th, 2007
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Matuzumab fails to show activity in Phase II trials for colorectal cancer

Merck Serano has announced that they are reconsidering developing matuzumab to treat metastatic colorectal cancer after a Phase II trial failed to show activity.  The trial combined matuzumab with irinotecan.

Patients enrolled in the trial had already had cancer get worse in other standard treatments, including irinotecan (Camptosar®).

Matuzumab is a fully humanized epidermal growth factor receptor inhibitor, blocking EGF receptors on tumor cells to keep cancer cells from dividing and tumors from growing.

Merck Serano will proceed with matuzumab clinical trials in other tumor types.

Posted by Kate Murphy on September 9th, 2007
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Hormone replacement therapy reduces colorectal cancer risk

Hormone replacement therapy (HRT) reduces the risk of colorectal cancer, but does so at the price of increasing risk for breast cancer.

Researchers in Italy followed almost 74,000 women who had at least one prescription for hormone replacement therapy between 1998 and 2000.  By 2005, nearly 3,700 of those women had been hospitalized for cancer.

Italian women who used HRT for more than two years had 20 percent less risk of colorectal cancer than those whose use was less than six months.  However, longer term HRT use increased risk of breast cancer by 34 percent.

Hormone replacement therapy delivered via a skin patch reduced breast cancer risk somewhat.  Long term users of a transdermal HRT patch had a 30% increased risk of breast cancer while those women who took oral HRT more than doubled their chances of getting breast cancer.

G. Corrao and colleagues at the University of Milan concluded,

Evidence that long-term use of HRT is associated with increased risk of breast cancer and decreased risk of colorectal cancer is supplied from this study from a southern European population. Our findings indicate that transdermal therapy might have lower effect than oral therapy in increasing breast cancer risk.

SOURCE:  Corrao et al, Annals of Oncology, online advanced access, September 4, 2007.

Posted by Kate Murphy on September 9th, 2007
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Why aren’t patients being screening for colorectal cancer?

Screening all men and women over the age of 50 for polyps would prevent a majority of colon and rectal cancers.  In addition, finding colorectal cancer early significantly reduces the risk of dying from the disease. Despite the recommendations, less than half of Americans are up-to-date with colorectal cancer screening.

Researchers at the University of Iowa examined patient charts for fifteen randomly chosen family practice doctors in rural Iowa, identifying patients who were screened and those who were not.  For each doctor in the study they selected 6 patients at random, 3 who had been screened and 3 who had not.

Focusing on those specific patients, they asked the doctors why the individual had been screened or why not.  Reasons for about half of those who were not screened were due to no discussion by the physician, another forty percent due to the patient refusing the doctor’s recommendation.

Reason that the doctor didn’t offer patients colorectal screening included:

• lack of opportunity — limited time, patients who only came to the doctor for acute illness
• doctor’s assessment that cost would be prohibitive
• distraction by patient’s acute health problems or life issues
• physician forgetfulness — lack of reminder systems
• expectation that patient would refuse

Reasons that patients refused included:

• cost
• lack of interest
• distraction by health problems or other life issues
• fear of screening exam
• lack of symptoms

Among the patients who were up-to-date with screening, half were tested because they had symptoms of colon or rectal cancer, and were not really screened. 

The words doctors used made a difference in whether the patient accepted the screening recommendation or not.  Language ranged from discouraging to neutral personal to strongly championing screening. 

Discouraging: “On the other hand, you probably don’t have colon cancer and, therefore, there’s a real good chance that doing this screening test won’t benefit you in any way other than giving you the peace of mind that you don’t have something that you weren’t even suspicious of.”

Championing: “‘The lifetime incidence of colon cancer approaches 8% in this country. If you were to cross the street and get run over 1 out of 10 times, which is essentially the same [risk], you would consider that a significant risk, so I think we ought to take a look [and do a colonoscopy].’ And sometimes I tell them that my father and my grandmother had colon cancer and that I’m an evangelist on the subject.”

The researchers wrote,

We found evidence that the words physicians use to present their recommendation for screening potentially impacts whether patients follow through with testing, based on higher physician-specific screening rates among physicians whose narratives demonstrated they were more adamant about screening and lower rates when physicians used terms like “they recommend” or “organization X recommends.”

Reasons for patients without symptoms who were up-to-date on their screening included:

• Doctor recommendation
• Patient’s own awareness of screening  and interest in it
• Patients with other cancers
• Family history of colorectal cancer
• Multiple factors including doctor recommendation, family history, personal patient awareness.

Barcey T. Levy, PhD, MD, and colleagues concluded,

Reasons many patients remain unscreened for CRC include (1) factors related to the health care system, patient, and physician that impede or prevent discussion; (2) patient refusal; and (3) the focus on diagnostic testing. Strategies to improve screening might include patient and physician education about the rationale for screening, universal coverage for health maintenance exams, and development of effective tracking and reminder systems. The words physicians choose to frame their recommendations are important and should be explored further.

SOURCE:  Levy et al, The Journal of the American Board of Family Medicine, Volume 20, Number 5, pages 458-468, September- October 2007

Posted by Kate Murphy on September 7th, 2007
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