Obese cancer patients often shorted on chemo doses

Obese people are less likely to survive cancer, and one reason may be a surprising inequality: The overweight are undertreated.

Doctors often short them on chemotherapy by not basing the dose on size, as they should. They use ideal weight or cap the dose out of fear about how much treatment an obese patient can bear. Yet research shows that bigger people handle chemo better than smaller people do.

Even a little less chemo can mean worse odds of survival, and studies suggest that as many as 40 percent of obese cancer patients have been getting less than 85 percent of the right dose for their size.

Now, the largest organization of doctors who treat cancer, the American Society of Clinical Oncology, aims to change that. The group has adopted guidelines urging full, weight-based doses for the obese.

Don't call it supersizing; it's right-sizing cancer care, said Dr. Gary Lyman, a Duke University oncologist who led the panel that wrote the advice.

"There's little doubt that some degree of undertreatment is contributing to the higher mortality and recurrence rates in obese patients," he said.



The Food and Drug Administration's cancer drug chief, Dr. Richard Pazdur, agrees.

"By minimizing the dose, or capping the dose, we have been undertreating patients," he said.

The dosing issue applies to all types of cancer treated with chemo — breast, colon, lung, ovarian and even blood diseases such as leukemia.

It affects a lot of people. Big isn't healthy but it's the new "normal" — 60 percent of Americans are overweight and more than one-third of them are obese.

Giving too little chemo "could make it as if they didn't even get treated at all ... so they go through the whole ordeal with no benefit, in the extreme case ," said Dr. Jennifer Griggs, a University of Michigan breast cancer specialist who also worked on the guidelines.

So why do doctors limit dose?

Sometimes it's for good reason — the patient has diabetes, heart problems or other illnesses that interfere with how much chemo they can stand. Usually, though, it's because doctors are afraid to follow a standard weight-based formula because the dose seems so huge and they're afraid of harming the heart and blood system, Lyman said.

"You're three times the size of the average person, but it doesn't mean your heart is," Griggs explained.

Yet studies show that heavier patients are less likely to develop dangerous, low blood counts from cancer treatment, and that they clear chemo drugs more quickly from the body than thinner people do.

A paper Lyman published in the journal Nature in August said that a 20 percent reduction in chemo doses lowered remission and cure rates by half in animal experiments and helped the tumors develop resistance to the drugs. Other research in people found lower survival among those getting less chemo as well.

Even if a patient develops a problem from a chemo treatment and doctors have to dial it back, it's important to try a full dose the next time around so the patient gets all the treatment intended, Lyman said.

That happened to Tracy Smith, a 46-year-old Durham, N.C., woman treated at Duke in 2011 for breast cancer that had spread to more than a dozen lymph nodes. Doctors gave her full chemo doses based on her weight, which at 285 pounds classified her as obese.

Three times, high fevers put her in the hospital, and one treatment was cut short because doctors thought it was causing wheezing and possible lung damage. But she resumed and finished the intended treatment and has been cancer-free since then.

After hearing you have cancer, "you're just kind of in a fog" and don't think to ask about doses of the drugs you need, she said. "I trusted my doctor. Doctors should be well aware of what you can tolerate. You should do whatever you can to fight this beast."

Smith's tumor was fueled by estrogen — a hormone made in abundance by fat tissue. Robin McRath, a floral designer who helps run a women's shelter in Ludington, Mich., had the same type.

"It's like a playground, an amusement park, for cancer cells when you're fat," she said. She was only was 41 when her cancer was diagnosed five years ago, and her oncologist, Dr. Carol Peterson, treated her with full doses based on her weight — about 240 pounds, which put her in the obese category.

"We didn't discuss dosage. That didn't matter to me — I just wanted to get it out of my system," she said of the cancer, and praised the treatments to prevent one of chemo's most feared side effects. "There are fantastic anti-nausea medicines. I was never sick one day."

McRath is active in the Obesity Action Coalition, an education and advocacy group. A spokesman said the group was unaware of the dosing issue for obese patients.

Not all doctors are aware either. Luckily for McRath, hers was. Peterson said she uses full doses unless a patient has other health issues.

"If that's their only problem — if they're just overweight or obese — they can do quite well" with full weight-based doses, she said.

Duke's Lyman agreed, and offered this advice to patients: "Ask your doctor how they plan to treat you and whether you're going to get the full dosing. The doctor may have a good reason not to, but you should have that discussion."

source: philstar.com

New surgical knife can instantly detect cancer

LONDON  — Surgeons may have a new way to smoke out cancer.

An experimental surgical knife can help surgeons make sure they've removed all the cancerous tissue, doctors reported Wednesday. Surgeons typically use knives that heat tissue as they cut, producing a sharp-smelling smoke. The new knife analyzes the smoke and can instantly signal whether the tissue is cancerous or healthy.

Now surgeons have to send the tissue to a lab and wait for the results.

Dr. Zoltan Takats of Imperial College London suspected the smoke produced during cancer surgery might contain some important cancer clues. So he designed a "smart" knife hooked up to a refrigerator-sized mass spectrometry device on wheels that analyzes the smoke from cauterizing tissue.

The smoke picked up by the smart knife is compared to a library of smoke "signatures" from cancerous and non-cancerous tissues. Information appears on a monitor: green means the tissue is healthy, red means cancerous and yellow means unidentifiable.

To make sure they've removed the tumor, surgeons now send samples to a laboratory while the patient remains on the operating table. It can take about 30 minutes to get an answer in the best hospitals, but even then doctors cannot be entirely sure, so they often remove a bit more tissue than they think is strictly necessary.


If some cancerous cells remain, patients may need to have another surgery or undergo chemotherapy or radiation treatment.

"(The new knife) looks fabulous," said Dr. Emma King, a head and neck cancer surgeon at Cancer Research U.K., who was not connected to the project. The smoke contains broken-up bits of tumor tissue and "it makes sense to look at it more carefully," she said.

The new knife and its accompanying machines were made for about £250,000 ($380,000) but scientists said the price tag would likely drop if the technology is commercialized.

The most common treatment for cancers involving solid tumors is removing them in surgery. In the U.K., one in five breast cancer patients who have surgery will need further operations to get rid of the tumor entirely.

Scientists tested the new knife at three hospitals between 2010 and 2012. Tissue samples were taken from 302 patients to create a database of which kinds of smoke contained cancers, including those of the brain, breast, colon, liver, lung and stomach.

That was then used to analyze tumors from 91 patients; the smart knife correctly spotted cancer in every case. The study was published Wednesday in the journal Science Translational Medicine. The research was paid for by groups including Imperial College London and the Hungarian government.

At a demonstration in London on Wednesday, doctors used the new knife — which resembles a fat white pen — to slice into slabs of pig's liver. Within minutes, the room was filled with an acrid-smelling smoke comparable to the fumes that would be produced during surgery on a human patient.

Takats said the knife would eventually be submitted for regulatory approval but that more studies were planned. He added the knife could also be used for other things like identifying tissues with bad blood supply and identifying the types of bacteria present.

Some experts said the technology could help eliminate the guesswork for doctors operating on cancer patients. "Brain cancers are notorious for infiltrating into healthy brain tissue beyond what's visible to the surgeon," said Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society. "If this can definitively tell doctors whether they've removed all the cancerous tissue, it would be very valuable," he said.

Still, Lichtenfeld said more trials were needed to prove the new knife would actually make a significant difference to patients. Early enthusiasm for new technologies hasn't always panned out, he said, citing the recent popularity of robotic surgery as an example.

"It expanded very rapidly but is now hitting some bumps along the road," he said.

Lichtenfeld said it's unclear whether more widespread use of the smart knife will actually help patients live longer and said studies should also look into whether the tool cuts down on patient's surgery times, their blood loss and rate of wound infections.

"This is a fascinating science and we need to adopt any technology that works to save patients," Lichtenfeld said. "But first we have to be sure that it works."

source: philstar.com

Chemotherapy can backfire and boost cancer growth: study

PARIS -- Cancer-busting chemotherapy can cause damage to healthy cells which triggers them to secrete a protein that sustains tumour growth and resistance to further treatment, a study said Sunday.

Researchers in the United States made the "completely unexpected" finding while seeking to explain why cancer cells are so resilient inside the human body when they are easy to kill in the lab.

They tested the effects of a type of chemotherapy on tissue collected from men with prostate cancer, and found "evidence of DNA damage" in healthy cells after treatment, the scientists wrote in Nature Medicine.

Chemotherapy works by inhibiting reproduction of fast-dividing cells such as those found in tumours.

The scientists found that healthy cells damaged by chemotherapy secreted more of a protein called WNT16B which boosts cancer cell survival.

"The increase in WNT16B was completely unexpected," study co-author Peter Nelson of the Fred Hutchinson Cancer Research Center in Seattle told AFP.

The protein was taken up by tumour cells neighbouring the damaged cells.

"WNT16B, when secreted, would interact with nearby tumour cells and cause them to grow, invade, and importantly, resist subsequent therapy," said Nelson.

In cancer treatment, tumours often respond well initially, followed by rapid regrowth and then resistance to further chemotherapy.

Rates of tumour cell reproduction have been shown to accelerate between treatments.

"Our results indicate that damage responses in benign cells... may directly contribute to enhanced tumour growth kinetics," wrote the team.

The researchers said they confirmed their findings with breast and ovarian cancer tumours.

The result paves the way for research into new, improved treatment, said Nelson.

"For example, an antibody to WNT16B, given with chemotherapy, may improve responses (kill more tumour cells)," he said in an email exchange.

"Alternatively, it may be possible to use smaller, less toxic doses of therapy."

source: interaksyon.com