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How much water do we really need? You may think six to eight glasses per day because you have probably read many articles and had discussions with your doctor to support that. But a Scottish physician has blasted that standard in a British Medical Journalarticle, stirring the debate about how much water we should drink and how much is too much and bad for our health. Dr. Margaret McCartney argues there is no quality scientific evidence to support the recommendation, which she says can lead to over-hydration problems for some people.
Here's what you need to know to sort hydration hype from good health advice.
Don't skimp
The eight-glass formula doesn't fit for everyone. It depends on your gender, size, and level of activity, other studies note. The Institute of Medicine calls for adult men to drink 13 cups of fluid daily (which totals three liters, or a little more than four tall reusable water bottles) and women to have nine cups (2.2 liters, or about the amount found in three reusable water bottles). That number changes according to lifestyle. The more active a person is, the more they will need to replace fluids. Larger people, pregnant and nursing women, and those who take dehydrating medications also will likely need to account for that by adding more water to their diet.
If you are active, it's also important to account for your environment when calculating how much fluid you need. If you are exercising in temperatures that are very hot (likely leading you sweat more) or very cold (which can stunt your ability to sense dehydration), are an endurance athlete, or are active in a high-altitude area, you will probably need to up your water intake. Don't overdo it
The debate about how much water we really need to be drinking is centered around the risk of hyponatremia, or taking in more fluid that the body loses while sweating. It is a serious condition that occurs when there is not enough sodium (or salt) in the body fluids outside of the cells. This can cause swelling, including of the brain. Hyponatremia happens when a person sweats excessively in one stint, does not eat, does not urinate enough, and drinks a great deal of water. Symptoms include confusion, headaches, muscle spasms, vomiting, convulsions, and fatigue. In the worst cases, hyponatremia can lead to seizures, coma, and even death.
There are exceptions for medical conditions and other situations, but athletes are often watched for signs of hyponatremia, especially those participating in endurance events like a marathon or triathlon.
Experts advise taking in some electrolyte-replacement fluids in addition to drinking water while you are exercising. However, you really only need a minimal amount to keep your body in balance and give you an energy kick. For example, it is recommended that runners out for 30 minutes to an hour take in three to six ounces of fluid every 15 or 20 minutes, including one sports drink. There's also evidence that simply taking sips or swishing a sports drink will do the trick.
Don't get sucked in to the sports drink hype
The risks of hyponatremia are steep, but take the hype about over-hydrating with a grain of salt. The multi-billion-dollar sports drink industry has pushed the idea that most people need more than water when they are active. However, some experts say that most people don't need a lot of sports beverages, and that they often just add calories to diets. The CDC recommends choosing sports drinks that do not have added sugar, which can total 38 grams in just one bottle. Count other drinks besides water as fluids
It's OK to include other drinks when you're measuring how many fluids you take in per day. However, that isn't a license to subsist on soda, coffee, and sugary drinks. Although caffeine in soda and coffee won't dehydrate you, they shouldn't be used to quench thirst or as a substitute for water. Add them to your fluid tally, but do reach for water more often than you pop open a can of bubbly stuff.
People who imbibe, particularly wine and hard liquors, should also be aware that those drinks with a high alcohol content can be dehydrating. Beer, however, is less dehydrating because it is predominantly water. Drinking a glass of water before and after alcohol can't hurt fluid intake or the chances of avoiding a headache the next day.
Eat your water
You don't always have to sip to stay hydrated. Experts say that 20 percent (or 2-1/2 cups) of the water we ingest comes from the foods we eat. Choosing the right water-rich fruits and vegetables will also add nutrients to your diet, fill you up, and may even give some oomph to your exercise.
Fruits like strawberries, cantaloupes, and peaches are packed full of water and potassium, which is the electrolyte shed when your body sweats. Adding more to your daily diet will help balance the fluids your body needs, regulate your heartbeat and circulation, and tastes better than chugging an energy drink.
Selecting foods that fuel your health while helping keep you hydrated will give you more bang for your buck. Watermelon offers a vitamin C boost, broccoli helps fight cancer, pineapple aids muscle recovery after a big workout, and yogurt ups immunity. (Read more about foods that keep you hydrated and healthy here.)
Sneak in the good stuff
If you're up to your ears in cucumber salad or can't manage to down another bottle of water, work in little ways to stay hydrated. Add slices of orange, lime, kiwi, or watermelon to a jug of water for a burst of natural flavor. Make a regular old glass of tap water feel fancier by adding fizz with a counter-top carbonator (sold for about $100 and marketed as home soda-makers, skip the added flavors to make sparkling water in your own reusable bottles). Take 10 minutes once a week to stock your fridge, car, gym bag, and desk with water bottles so it's convenient to grab water wherever you spend most of your day. Finally, you can up your fluid intake with one little step by simply adding a straw to your glass of water.
Results from the landmark National Lung Screening Trial (NLST), which indicate that screening with low-dose helical computed tomography (CT) reduces mortality from lung cancer, have been published online in the New England Journal of Medicine.
The 53,000-person trial found a 20% reduction in deaths from lung cancer among current and former heavy smokers screened with low-dose helical CT, compared with those screened with chest radiograph (P = .004); the study has a median follow-up of 6.5 years. These principal findings were first reported publicly in October 2010, and were covered at the time by Medscape Medical News.
The newly published paper includes previously unavailable details on the diagnostic procedures performed after positive screenings and their related complications rates, as well as details on the lung cancers that were diagnosed.
The study has been accompanied by expressions of enthusiasm and gratitude from the American oncology community.
"It's gratifying. We've been looking for this kind of good news in lung cancer for a long time," Otis Brawley, MD, chief medical officer at the American Cancer Society (ACS), told Medscape Medical News.
"This study fills a huge gap in lung cancer control," said Bruce Johnson, MD, in a press statement from the American Society of Clinical Oncology, where he is a board member. "This is a very exciting and important result," added Dr. Johnson, who is from the Dana-Farber Cancer Institute in Boston, Massachusetts.
The positive study results beg the question of whether or not it is time for lung cancer screening programs in the United States.
The study authors, led by Christine Berg, MD, from the National Cancer Institute, think the evidence is not complete enough yet. "The current NLST data alone are . . . insufficient to fully inform such important decisions [on lung cancer screening recommendations]."
The authors have estimated the immensity of the potential impact of such policies.
Although there are only 7 million adults in the United States who meet the entry criteria for the NLST, there are an estimated 94 million adults who are current or former smokers, and thus potential screens, they suggest.
Whatever the target population, "a national screening program of annual low-dose CT would be very expensive," writes Harold Sox, MD, from Dartmouth Medical School in West Lebanon, New Hampshire, in an editorial that accompanies the NLST study. "I agree with the authors that policy makers should wait for more information before endorsing lung cancer screening programs," he writes, citing cost as his principal objection.
However, one clinician has seen enough data to endorse screening.
"There should be a national screening policy, with CT offered to and even recommended for all patients who meet the same criteria as the eligibility for the NLST," said Howard West, MD, from the Swedish Cancer Institute in Seattle, Washington, and author of the Blowing Smokelung cancer blog.
If such a policy is not forthcoming, the lung cancer community, including medical professionals, "should ask the government and insurance company leadership why they so clearly devalue the lives of people with lung cancer, compared with those afflicted with other cancers," Dr. West toldMedscape Medical News.
Dr. West said that if results of this magnitude were seen in other cancers, especially breast cancer, there would be no questioning the cost of the screening. "Screening in other cancers that is widely accepted is based on far, far less impressive improvement in actual survival," he said.
"Our society routinely places a very different threshold for acceptance of lung cancer interventions than breast cancer interventions, which are often routinely and unquestioningly accepted as worthwhile interventions based on remarkably minimal absolute differences in outcomes," he pointed out.
"There is nothing less valuable about a life saved from lung cancer than a life saved from breast cancer or another cancer," said Dr. West.
Dr. Brawley suggested that professional opinion will influence forthcoming lung cancer screening policy. The ACS began drafting a lung cancer screening guideline when the NLST results were first announced. The ACS guideline will now be informed by the paper's new data, as well as by the medical communities' reaction to it, said Dr. Brawley. The ACS will be "monitoring the 'Letters to the Editor' reaction to the paper," he said.
Concerns About Harms
In NLST, participants were between 55 and 74 years of age and had a history of heavy smoking. They were screened once a year for 3 years, and were followed for 3.5 additional years with no screening.
There were 247 deaths from lung cancer per 100,000 person-years in the low-dose CT group and 309 deaths per 100,000 person-years in the radiography group, which is a relative reduction in mortality from lung cancer with low-dose CT screening of 20% (95% confidence interval [CI], 6.8 to 26.7).
The number needed to screen with low-dose CT to prevent 1 death from lung cancer was 320, Constantine Gatsonis, PhD, one of the study coauthors, told Medscape Medical News. He is from the Warren Alpert Medical School of Brown University in Providence, Rhode Island.
The rate of positive screening tests was more than 3 times higher with low-dose CT than with radiography (24.2% vs 6.9%) over all 3 rounds.
Most of the positive tests were false — 96.4% of the positive screening results in the low-dose CT group and 94.5% in the radiography group were false-positive results.
"The rate of false positives is very high, although the thoracic/pulmonology communities have certainly seen high rates of false positives with screening in the past," noted Dr. West.
The authors address the issue of false positives. "The vast majority of false-positive results were probably due to the presence of benign intrapulmonary lymph nodes or noncalcified granulomas," they write.
In a related concern, they note that the rates of complications after a diagnostic evaluation procedure for a positive screening test were "low." The rate of 1 complication or more was 1.4% in the low-dose CT group and 1.6% in the radiography group. The diagnostic methods and algorithms varied at the 33 sites and were not uniform per the protocol, the authors point out.
Dr. Sox observes that invasive diagnostic procedures were "few, suggesting that diagnostic CT and comparison with prior images usually sufficed to rule out lung cancer in participants with suspicious screening findings."
Dr. West said that lung screening is akin to prostate-specific antigen monitoring for prostate cancer. "Undergoing CT screening for lung cancer will require a careful discussion of the road that this may well lead people down, including the anxiety, additional imaging, and potentially invasive procedures that this pathway might well entail," he said.
The study authors point to another finding from the NLST as proof of the relative safety of lung cancer screening. The rate of death from any cause was reduced in the low-dose CT group, compared with the radiography group, by 6.7% (95% CI, 1.2 to 13.6; P = .02). "The decrease in the rate of death from any cause with the use of low-dose CT screening suggests that such screening is not, on the whole, deleterious," they conclude.
Another concern with CT screening is overdiagnosis, says Dr. Sox.
"Overdiagnosis probably occurred in the NLST," he writes. After 6 years of observation, there were 1060 lung cancers in the low-dose CT group and 941 in the radiography group. This may be evidence of overdiagnosis because, in a large clinical trial of screening tests, "the proportion of patients in whom cancer ultimately develops should be the same in the 2 study groups," he said. If the difference found to date between the 2 screening methods persists with more follow-up, this "suggests that one test is detecting cancers that would never grow large enough to be detected by the other test," Dr. Sox notes.
Finally, the study authors cite one last safety concern with CT screening — cancer caused by the CT scans themselves. "The association of low-dose CT with the development of radiation-induced cancers could not be measured directly," they write, adding that it is a "long-term phenomenon." Dr. Brawley said that previous research has indicated that for every 2000 spiral CT scans, there is at least 1 cancer caused (Radiology. 2004;232:735-738).
Cancers Detected
Low-dose CT screening fulfills an often-touted claim about cancer screening — that it detects more cancers earlier than would have been likely detected clinically. Indeed, 40% of the cancers in the low-dose CT group were stage 1A, whereas 21.7% were stage IV.
"Cancers discovered after a positive low-dose CT screening test were more likely to be early stage and less likely to be late stage than were those discovered after chest radiography," Dr. Sox explains.
Will the benefits of screening seen in the NLST be seen in community settings? Dr. Sox believes the applicability of the results is "mixed."
Diagnostic work-up and treatment did take place in the community, he acknowledged. "However, the images were interpreted by radiologists at the screening center who had extra training in the interpretation of low-dose CT scans and presumably a heavy low-dose CT workload," he writes.
Furthermore, both Dr. Sox and the study authors point out that the study population was not typical. Trial participants were younger and had a higher level of education than a random sample of men and women with a history of heavy smoking. This might have contributed to the high rate of adherence to the screening protocol in the study (more than 90%), says Dr. Sox.
The influential US Preventative Services Task Force (USPSTF) will make a determination about recommendations for lung cancer screening "by next year," said Dr. Brawley. In the meantime, while the USPSTF and organizations such as the ASC, which helped fund the study, and the American College of Radiology make their recommendations, physicians and patients should have a conversation about the harms and benefits of screening, he said.
Dr. Brawley, while emphasizing concerns about low-dose CT screening, said that "it's wonderful that we can say to high-risk people: 'We have something to offer you folks."
The study was conducted by the American College of Radiology Imaging Network and the National Cancer Institute's Lung Screening Study Group.
NEW YORK (Reuters Health) Jun 16 - Breast-conserving therapy may provide better five-year locoregional control for women with triple-negative breast cancer than modified radical mastectomy without adjuvant radiation, according to a retrospective study from Canada.
National Comprehensive Cancer Network guidelines recommend adjuvant radiotherapy after modified radical mastectomy based only on tumor size and lymph node status, without regard to biologic subtype.
But the new results challenge the "paradigm in breast cancer that breast-conserving surgery followed by radiation therapy is equivalent to mastectomy alone" in all patients, said Dr. Jean-Philippe Pignol of Sunnybrook Health Sciences Centre in Toronto and colleagues in an editorial.
Instead, mastectomy for aggressive disease like triple-negative breast cancer may be the wrong approach, they wrote.
As reported online June 13 in the Journal of Clinical Oncology, Dr. Bassam Abdulkarim and colleagues at McGill University in Montreal reviewed all cases of triple-negative breast cancer at their institution from 1998-2008 (n=768), i.e., all women whose tumors didn't express receptors for estrogen, progesterone, or human epidermal growth factor receptor-2 (HER2).
As initial treatment, 42% of patients received breast-conserving therapy, 37% had modified radical mastectomy alone, and 21% had modified radical mastectomy plus adjuvant radiotherapy. Eighty-five percent received chemotherapy. The median follow-up in the study was 7.2 years.
Five-year, locoregional recurrence-free survival was 94%, 85%, and 87% for breast-conserving therapy, modified radical mastectomy and modified radical mastectomy plus radiotherapy, respectively (P<.001).
When investigators analyzed only the type of initial treatment, the rate of locoregional recurrence was significantly higher in the modified radical mastectomy group (HR, 2.61, P<.001) and the modified radical mastectomy plus radiotherapy group (HR, 2.38, P<.001) compared to patients receiving breast conserving therapy.
When they analyzed multiple variables, including tumor size, grade, lymph node status, lymph vascular invasion and adjuvant chemotherapy, modified radical mastectomy without radiotherapy was an independent predictor of local recurrence (HR 3.44, P<.001) however, there was no difference between those who also underwent radiotherapy and those who received breast conserving therapy.
The investigators also looked separately at 468 women with T1-2N0 disease. In this group, five-year locoregional recurrence-free survival was 96% after breast-conserving therapy and 90% after modified radical mastectomy without radiation (P=.022). On multivariate analysis, modified radical mastectomy without radiotherapy was the only independent factor associated with higher local recurrence (HR, 2.53, P=.027).
"Taken together, our findings emphasize that the current guidelines should take into account the intrinsic risk associated with this biologic subtype," the investigators, the authors say.
In their editorial, Dr. Pignol and colleagues say that clinically, the data should be used to inform triple-negative breast cancer patients of their likely outcomes. Also, they suggest, "adjuvant radiotherapy after mastectomy should at least be discussed" with such women.
New data from the United Kingdom show that prostate cancer kills half of the men diagnosed with this disease, and challenge the notion that prostate cancer patients "are more likely to die with, rather than of, their disease," according to the researchers.
The situation is much different in the United States, where recent estimates suggest that only about 15% of men diagnosed with prostate cancer die from this disease.
The main reason for this huge difference is the high uptake of testing for prostate-specific antigen (PSA) in asymptomatic men in the United States, and the low uptake in the United Kingdom, say experts on both sides of the Atlantic.
Both situations are described as extreme by those on the other side. British researchers say that routine PSA testing in the United States is picking up disease that might be clinically insignificant, leading to overdiagnosis and overtreatment of prostate cancer. American researchers argue that PSA testing is picking up prostate cancer at an earlier stage of disease, when it is still treatable and curable, which results in the much lower mortality rates.
"If you are screening too aggressively, there is no question that you will overtreat, but the other end of the spectrum is that you have a cancer that is very curable but you still end up having half of the patients dying of the disease because they are presenting at late stages" said Brantley Thrasher, MD, FACS, professor of urology at the University of Kansas in Kansas City, who acts as a spokesperson for the American Urological Association.
"I would rather have the potential — and I emphasize the potential — for overtreating than swing the other way and lose all of these patients to a disease that is curable," Dr. Thrasher explained in an interview with Medscape Medical News.
New British Analysis
The new British data come from an analysis of 50,066 men diagnosed with prostate cancer between 1997 and 2006 from the Thames Cancer Registry, which covers a population of 12 million in South East England. Subjects were followed to the end of 2007.
During that period of time, there was little uptake of PSA testing in asymptomatic men in the United Kingdom.
The situation is different in the United States, where there is a high uptake of PSA testing, and has been for some time, lead researcher Simon Chowdhury, MD, consultant oncologist at Guy's and St Thomas' NHS Foundation Trust in London, United Kingdom, told Medscape Medical News.
Dr. Chowdhury presented the findings at the 2011 Meeting of United Kingdom Association of Cancer Registries and National Cancer Intelligence Network (NCIN), held in London.
The analysis found that prostate cancer was the cause of death in 49.7% of the men who had been diagnosed with the disease. The other causes of death were cardiovascular disease (17.8%), other cancers (11.8%), pneumonia (7.5%), and other causes (13.25%).
Prostate cancer remained an important cause of death even when the data were analyzed according to age, cancer stage, and first treatment, the researchers note.
Prostate cancer was the cause of death in 74.3% of men who had stage IV cancer at diagnosis, in 46.4% of all men 75 years and older, and in 31.6% of all men who underwent radical prostatectomy.
"Prostate cancer was the underlying cause of death in a substantial proportion of men," the researchers conclude, "and remained an important cause of death in all subgroups, including those treated with curative intent and older men."
"Our data show that a high proportion of men with prostate cancer die from the cancer," commented study author Henrik Møller, BA, BSc, MSc, DM, FFPH, professor of epidemiology at King's College London, and director of the Thames Cancer Registry. Dr. Møller, who is also head of analysis and research at the NCIN, added: "Our findings challenge the commonly-held view that most men with prostate cancer will die with the disease, rather than from it."
Setting of Low PSA Testing
The British researchers point out that their findings pertain to settings where there is a low uptake of PSA testing in asymptomatic men. In such a setting, "our findings challenge the notion that prostate cancer is a negligible problem in any subgroup, as defined by age, stage, or treatment," they note.
Dr. Chowdhury explained in an interview with Medscape Medical News that PSA testing was introduced in the United Kingdom in the early 1990s, but it is not routinely performed in asymptomatic men.
The situation is different in the United States, where there is a high uptake of PSA testing, with reports that more than 50% of men older than 65 years of age are tested, and many of the men tested are asymptomatic. This PSA testing in asymptomatic men might result in overdiagnosis and overtreatment of prostate cancer, Dr. Chowdhury said, because "some of the prostate cancers that are picked up are small and some may be clinically insignificant."
Dr. Chowdhury noted that the ratio of prostate cancer deaths to prostate cancer diagnoses is very different in the 2 regions — about 1 to 6.0 in the United States (based on estimates from the 2010 SEER database, showing a diagnosis in 215,000 men and 30,000 deaths) and about 1 to 3.7 in the United Kingdom (based on 2008 Cancer Research UK data, which show that there were 37,000 diagnoses and 10,100 deaths from prostate cancer).
There is a difference in the stage of prostate cancer at diagnosis — some American reports suggest that about 80% of the disease is localized, whereas in the United Kingdom, although most disease is also localized, there is a higher proportion of cancers diagnosed at an advanced stage, Dr. Chowdhury explained. Widespread PSA testing picks up prostate cancer at an earlier stage, which might be less aggressive and less clinically significant, he said.
"Not a Trivial Disease"
This is an extremely important study, which highlights the fact that prostate cancer is not a trivial disease for a large number of men in the United Kingdom who suffer from it," said Malcolm Mason, MD, head of oncology and palliative medicine at Cardiff University School of Medicine, United Kingdom. Dr. Mason is also chair of the UK National Cancer Research Institute's Prostate Cancer Clinical Studies Group, and was commenting in a statement issued by Cancer Research UK.Particularly for men with advanced prostate cancer, their disease poses a significant threat to their health and their life, and the old notion that 'most men die with it, not of it' is simply not true."
Since that study was carried out, there have been a number of important advances in treatment, Dr. Mason noted. "It is possible that not all of the men in this study who died of prostate cancer would die of it today with modern treatment," he said. In addition, many more men are diagnosed at a much earlier stage; for these men, the outlook is excellent, even without treatment, he added.
Need for Earlier Diagnosis and Treatment
Dr. Thrasher agreed with the conclusion that prostate cancer is not a trivial disease. "This study highlights the fact that prostate cancer can be a deadly disease," he said. "It speaks volumes about what happens when the cancer is advanced and out of the confines of the organ — it will kill you."
These data add weight to the argument for screening for prostate cancer, he said. They reinforce the need for earlier diagnosis and earlier treatment of the disease, and although the PSA test has its problems, it does result in both.
"There is no question that this is happening in the United States; we are finding and treating prostate cancer earlier," he said.
Dr. Thrasher cited 2010 estimates, from the Cancer Journal for Clinicians,that there were 217,000 new cases of prostate cancer diagnosed in the United States and 32,500 cancer deaths, which gives a mortality rate from the disease of 15%. In the United Kingdom, the rate is 50%.
There is a similar situation in Japan, he noted, where there is no routine PSA screening. Dr. Thrasher explained that he recently had the opportunity to talk to Japanese urologists during a joint meeting of the American and Japanese urological associations in Hawaii, and they were saying that by the time they see prostate cancer, it has often advanced to a stage where it is inoperable and not suitable for radiation.
Dr. Thrasher acknowledged that routine PSA testing can lead to the overdiagnosis and overtreatment of prostate cancer that might not be clinically significant. "We are starting to see some pullback as a result of this," he said, and although it is slow to gain ground in the United States, there is more use now of active surveillance as a treatment option, he told Medscape Medical News."We are starting to do this, especially in older men with low-grade, low-volume disease," he said. "However, right now, that is not mainline, and it is not a standard of care," he emphasized: "It is one option."
The very real benefit from PSA testing — finding prostate cancer at an earlier stage of disease, when it is still curable, which saves lives — has to be weighed against the potential for overdiagnosis and overtreatment, and the potential for anxiety from routine testing, he concluded. These latest data from the United Kingdom show that when there is no PSA testing, "you are losing about half your patients to the disease, and so it lends credibility toward leaning the other way," he said.
2011 Meeting of United Kingdom Association of Cancer Registries and National Cancer Intelligence Network (NCIN): Abstract 86. Presented June 16, 2011.
