A folk song performed by a tongue cancer patient from Sichuan Province was not too fluent or clear, but it was full of hope and joy.

The man's song was music to the ears of Professor Kang Jingxuan, a cancer researcher at Harvard University Medical School, and 12,000 cancer patients and survivors at the "Smile at Life" gala at the Mercedes-Benz Arena. They gathered in mid-January during a Spring Festival celebration organized by the Shanghai Cancer Rehabilitation Club, a 20-year-old support group.

Kang, a 50-year-old Chinese American, is director of the Harvard's Laboratory for Lipid Medicine and Technology. He flew to Shanghai to celebrate with patients, especially the man with advanced tongue cancer who adopted Kang's diet suggestions and reported dramatic improvement in six months. The cancer appears to be in remission.

Oncologists, who are not familiar with that particular case, decline to comment on specifics but they say they cannot conclude dietary treatment caused the improvement. They emphasized that dietary treatment for cancer has not been proved and needs extensive, large-scale human testing.

They also say the body needs good general nutrition and protein to help patients stay strong while they undergo radiation and chemotherapy. Some aspects of nutrition therapy may be useful in conjunction with other treatments, they say.

Kang himself says his approach is not mature yet.

The patient from Sichuan, whose name was not provided by organizers, met Kang in Shanghai last summer and decided to adopt his general dietary suggestions.

"Professor Kang saved my tongue and my life when I was desperate; there's no better way to show my gratitude than to use my tongue and sing for him," the man told the audience.

His cancer was so advanced that he could neither eat nor speak, and doctors had recommended removal of his tongue. Years ago part of his tongue had been removed but he did not have chemotherapy or radiation. He went into remission but the cancer recurred last summer. Doctors recommended removal of the entire tongue but he could afford surgery and instead took traditional Chinese medicine.

Last summer he heard Kang was in Shanghai and came to meet him. That's when he learned about diet; it was a general suggestion, not a prescription and was not presented as a possible cure, organizers say.

"I did not advise him to stop taking TCM medicine but recommended he take omega-3 supplements, adjust his diet, get regular exercise and try to maintain an optimistic mood," Kang told Shanghai Daily in an interview in Shanghai before the January gala. "Surprisingly, he regained speech in weeks and had no need of surgery."

The diet is similar to what's called an "anti-inflammatory diet," plus large supplements of omega-3 essential fatty acid (found in oil fish), which fights inflammation and is said to have anti-cancer properties, among other benefits.

In general the diet is very low in omega-6 fatty acid, low in sugar, low in animal protein, low in "bad" fats, low in processed foods, high in antioxidants from fresh fruits and vegetables, high in fiber, whole grains and nuts.

Cancer researcher Kang is a regular consultant to the Shanghai Cancer Rehabilitation Club, occasionally visiting, lecturing and taking long-distance telephone questions. He does not see patients or write prescriptions.

Hospital oncologists point out that Kang is a researcher, not a physician or an oncologist and question the propriety of his link-up with a cancer support group where many people are desperate and seeking new treatments.

Controversial

Dietary therapy for cancer is controversial. Still, there are various diets that help keep cells healthy and reduce chances of ailments. They are generally similar to Kang's regimen - high in omega-3, high in antioxidants, low in animal fat and so on.

Kang has been searching for safe and effective cancer treatments for almost seven years. His focus is nutrition, which he believes is the key to solving many health problems today.

Since 1994 he has worked at Harvard University Medical School, after graduating in 1993 with a PhD from the University of Alberta in Canada. He graduated from Guangdong Medical College in 1984.

"Everybody knows correct nutrition is crucial for health but people don't know much about it," Kang says. Careful nutrition choices and control of diet can prevent and cure certain diseases, he says.

He cites great overconsumption of omega-6 and insufficient omega-3, both essential fatty acids, as a major cause of health problems. These include cancers, heart disease and generally "sub-healthy" status.

The body does not manufacture omega-6 and omega-3, so they must be obtained from food or supplements. Omega-6 is found almost everywhere in processed foods and snacks - intake in modern diets is enormous - but omega-3 is rare and found mainly in oily, cold water fish and flax seeds.

Both are needed to make hormones, but those from omega-6 tend to fuel inflammation (an important component of immune response), blood clotting, and cell proliferation; while those from omega-3 fatty acids decrease those functions. Excessive inflammation has been linked to many cancers.

Kang was nominated for the Nobel Prize in Medicine in 2006 for successfully developing the first mammal capable of manufacturing omega-3; previously only deepwater fish were known to produce it.

After researching the use of omega-3 in preventing and treating heart disease by reducing blood fat and reducing inflammation, Kang shifted his attention to cancer treatment in 2005.

There is almost no effective medicine for treatment and cure, Kang says. "But that doesn't mean it's not curable since medication is one way, but not the only way to fight diseases."

Though most medical scientists focus on medication and treatments to kill cancer cells or inhibit growth, Kang looks for other ways to keep people cancer free and help patients get better, or at least feel better.

Though cancer cells may be killed or removed surgically, cancer still may spread, requiring further painful chemotherapy and radiation. Many cancer patients develop tolerance to the powerful cancer-killing drugs.

"Chemotherapy and radiation are effective but their indiscriminate attack on cells causes great suffering and the micro-environment for cell growth remains unchanged, so the cancer may recur elsewhere," Kang says.

Good nutrition is key to a healthy micro-environment on the cellular level but cancer cells also need nutrition, or they cease growing or shrink.

"We need to support normal cell metabolism, so the task is finding cancer cells' particular needs. Rob it of what it needs and supply what it doesn't," Kang says.

Rather than drawing up a list of different nutrients for different cancers, Kang and his group are looking for commonalities, trying to develop a list of universal effectiveness.

The approach is similar to the TCM concept of reinforcing healthy qi (energy flow) and driving out pathogenic qi, but Kang focuses on the cellular level, rather than the vague idea of qi.

"There must be common characteristics shared by different kinds of growing cancer cells and as we find them, we can make a list," Kang says.

For example, some inflammation and vascular proliferation (growth of blood cells within tumors) are common in cancer growth, regardless of location. This suggests the value of nutrition to fight inflammation, oxidation and blood vessel proliferation.

Since he started consulting last year for the Shanghai Cancer Rehabilitation Club, most patients adopting his diet suggestions report they feel better, Kang says.

Nutrition therapy may be more effective for cancers involving the digestive system, but the patient's attitude is also important, Kang says.

"Though my nutrition intervention therapy is not mature yet, it works well on some patients and helps many improve their quality of life," Kang says. "It's worth trying and trying itself provides hope and strength."

Diet therapy questioned

The idea of controlling cancer by controlling nutrition supply is not new, and it may be perfect in theory but not necessarily effective in real practice, according to Dr Lu Shun, chief of the Lung Cancer Clinic of the Shanghai Chest Hospital.

"I know of relevant laboratory tests on animals but there is no solid proof so far of its effectiveness in humans," Dr Lu says. "What works in animals may not necessarily work on humans."

He is concerned about lack of all-round nutrition and sufficient protein.

"Generally, we still advocate sufficient nutrition so cancer patients are strong enough to take the standard treatments of radiation and chemotherapy," Dr Lu says.

Oncologist Dr Han Baohui of the Shanghai Chest Hospital also doubts the effectiveness of nutrition therapy alone.

"I have worked in cancer treatment for almost 30 years, and I know how intractable tumors are," Dr Han says.

"Treating cancer by nutrition adjustment alone is not realistic. It may help as a supplementary means, but more evidence is needed. Limited successful cases, even a few hundred, are not that convincing for most people in the cancer treatment field."