Tall people at greater risk of cancer ‘because they have more cells’
Report suggests link between height and cancer risk could simply be because there are more cells for something to go wrong in.
Taller people have a greater risk of cancer because they are bigger and so have more cells in their bodies in which dangerous mutations can occur, new research suggested, theguardian.com reported.
A number of studies have previously found a link between a lofty stature and a greater risk of developing some form of cancer, with research suggesting that for every 10 centimeters (cm) of height within the typical range for humans, the risk increases by about ten percent. A similar link has also been found in dogs, with bigger breeds having a greater risk of such diseases.
Scientists have put forward a number of different explanations for this, including that certain growth hormones could play a role in both height and cancer, or that environmental factors such as childhood nutrition or illness could be a factor.
“One of the major hypotheses was that something was happening early in life that was making your cells more susceptible to cancer and, sort of incidentally, causing you to be tall,” said Leonard Nunney, a professor of biology at the University of California Riverside.
Nunney said he has crunched the numbers to show it might be down to a simpler matter of size: Tall people simply have more cells for something to go wrong in.
Nunney said his work, published in the Proceedings of the Royal Society B, is based on the fundamental model of how cancer develops, whereby individuals accumulate mutations in their cells (other than sperm or eggs) over their life: If a particular set of mutations arise then a certain cancer will initiate.
The theory suggests that having more cells, or more divisions per cell, would therefore increase cancer risk.
Nunney compared the overall risk of men and women developing cancer of any type with increasing height, as found from previous studies of large cohorts, with what might be expected from calculations based on the number of cells in a body.
The results reveal that his predictions are in tune with the reallife observations, giving a 13-percent increased risk for women for every additional 10cm in height compared with 12 percent from observations, and an 11-percent predicted increase in men for every 10cm taller compared with 9 percent seen in real life.
Overall, an increased risk with height was seen for 18 out of 23 cancers considered.
Nunney said some cancers may have shown no link because the effect of height was masked by other drivers.
Nonetheless, Nunney said the findings suggest sheer number of cells is important.
“Whether that comes from a better diet or the fact that your parents happen to be tall doesn’t matter … it is purely a number of cells, however that comes about,” he said, although he admitted height differences only appear to partly explain why men are at greater risk of many cancers than women.
The research also threw up some surprises: For example, the skin cancer melanoma shows a much stronger link to height than expected — something Nunney suggested might be down to taller people having slightly higher levels of a growth hormone called IGF-1.
Nunney said a slight boost in the rate of cell division, as a result of higher levels of IGF-1, might have a stronger effect on these cells than it does in other tissues, possibly because melanoma might need a larger set of mutations to develop than other cancers.
Professor Dorothy Bennett, the director of the Molecular and Clinical Sciences Research Institute at St. George’s, University of London, welcomed the research, although she said Nunney’s calculations involved a number of assumptions, including that cancer risk increases in direct proportion to adult height.
But she said the argument was compelling: “The simplifications seem reasonable, and therefore the main study conclusion is probably going to be the best-supported one available at present: Namely that for most cancer types, cell number can predict sufficiently well the numerical relations between height and cancer, with no need to suggest additional factors.”
Bennett said there was no obvious reason melanoma should have a particularly strong link to height.
Georgina Hill, from Cancer Research UK, said individuals should not be concerned about their stature.
“A number of studies over the years have shown that taller people seem to have a slightly higher risk of cancer,” she said.
“But the increased risk is small and there’s plenty you can do to reduce the risk of developing cancer, such as not smoking and keeping a healthy weight.” She became a doctor to serve communities like the one she grew up in.
Her patient suffered a high-risk pregnancy and faced a serious complication, CNN reported.
The experiences of these two women, doctor and patient, shed light on the state of maternal healthcare impacting immigrant women in the US.
Earlier this year, the patient’s blood pressure inched higher and higher. Her pregnant body felt ‘strange and different’, and obstetrician Dr. Cristina Gamboa became increasingly concerned.
Gamboa and her colleagues at Salud Para La Gente, a community health center in Watsonville, California, quickly changed their patient’s delivery plan to perform a repeat cesarean section after diagnosing the patient with preeclampsia. Moments later, the patient gave birth to a healthy baby girl.
“Preeclampsia is one of the leading causes of maternal death and timely diagnosis is important,” Gamboa said.
High blood pressure disorders during pregnancy are due to various changes in the body. So preeclampsia, a complication characterized by high blood pressure and other features, and other pregnancy issues, are not directly caused by stress but stress can play an important role, Gamboa said.
The blood pressure-raising stress seen in Gamboa’s patient during her pregnancy has become an increasingly common trend that Gamboa has seen at Salud Para La Gente, which has centers in California’s Santa Cruz and Monterey counties.
She has seen increased stress specifically among pregnant patients who happen to be Mexican immigrants in the US. Among the patients at Salud Para La Genta in Watsonville, about 40 percent are farmworkers and 92 percent are Hispanic, said Gamboa, who herself grew up in a farming town and belongs to an immigrant family.
While several factors can drive stress — such as employment status, social instability or preexisting health conditions — one additional factor in recent years for immigrant women has been America’s political climate, Gamboa said.
The stress that some mothers face can make them at higher risk for depression and anxiety, which potentially can impact the baby’s health too, Gamboa said.
“We screen all of our moms for depression in pregnancy, regardless of immigration status, so we do find that more of our more recently immigrant moms have a higher rate of depression and other mood disorders of pregnancy,” she said.
“The time that we live in and the administration that governs us, I see it affecting patients.”
In general, it is a crime for anyone to enter into the US without the approval of an immigration officer, and overstaying a work or travel visa is a civil violation.
In 2015, there were about 11 million unauthorized immigrants in the US. Of these, about one-quarter resided in California — more than in any other state in the US.
‘Every immigrant is different’
Gamboa’s patient, whom CNN has agreed to keep anonymous for her safety, experienced that highrisk pregnancy earlier this year due to preeclampsia, gestational diabetes, and a history of two previous cesarean sections.
“With the new administration, it’s a tense moment,” the patient said in the documentary titled ‘Giving Birth in America: California’, produced by Every Mother Counts, a nonprofit that seeks to raise the profile and issues of maternal health in the US.
“Sometimes you wake up in the middle of the night, at two in the morning — supposedly in the last weeks of pregnancy is when you should be most relaxed, most calm — that ICE is here, ICE is there, sometimes I’m even scared to go to the doctors,” said the patient, who works picking strawberries.
“During the entire pregnancy, seven or eight months back, I never had high blood pressure, never — because before I made my payments, I paid my phone bill, my insurance, everything. I didn’t have any stress,” she said.
“But when I couldn’t do it anymore, it became a huge weight on me. A lot of stress, it was too much.”
High blood pressure occurs in about six percent to eight percent of all pregnancies among women, ages 20 to 44, in the US, and every year two percent to 10 percent of pregnancies in the US are affected by gestational diabetes, according to the Centers for Disease Control and Prevention.
The scientific literature remains unclear on exactly how a woman’s immigration status may impact the health of her pregnancy or childbirth. More research is needed to determine whether immigrant women in the US have higher or lower rates of pregnancy complications than Us-born women, Gamboa said.
“Not all immigrants are the same. The country of origin, the time of duration that an immigrant has been in the United States, has been shown to be correlated with certain health outcomes,” she said.
“Because every immigrant is different, the literature to clearly describe immigration disparities in maternal health is still lacking, and so there’s limitations to small population sizes and demographic characteristics.”
Some studies suggest that in industrialized countries, an immigrant woman’s country of origin is associated with whether she may have a higher or lower risk of complications, such as preeclampsia. Other studies point out that the stress of migration and targeted raids could be associated with adverse birth outcomes.
While research into maternal health disparities seen among immigrant populations appears to be lacking, one disparity remains obvious: Access to healthcare.
“Studies have shown later entry to prenatal care and/or no care at all for pregnant women who have more recently migrated to our country,” Gamboa said.
“They’ve also been shown to have a higher rate of preterm birth, which could be linked to the limited access in care or other factors,” she said.
“Another important thing to highlight is that the social context that immigrant women live in can deeply impact health outcomes,” she said.
“An immigrant recently arrived may have limited or no social support system, limited transportation, limited language abilities and cultural barriers that may not allow them to access the healthcare system the way someone else would if they’d been here for their whole life or are English speakers.”
She added that those factors are called ‘social determinants of health’, and are important to evaluate when caring for a patient.
Gamboa added that, due to the fear of having their immigration status exposed, some women might not access the health resources available to them, which also could put a pregnancy at risk.
“In California, we have the availability to provide insurance to all expecting mothers, regardless of immigration status, called pregnancy-related Medi-cal,” she said.
Medi-cal covered nearly half of all births in California in 2014, and in 2011, one-third of Medical births were to undocumented women, according to the nonprofit California Health Care Foundation.
“But other programs — such as food assistance programs, Migrant Head Start, WIC [the Special Supplemental Nutrition Program for Women, Infants, and Children] — a lot of the patients are saying that they’re hesitant to sign up because they’re afraid their information could be used to track them, to find out that they’re here unauthorized and notify authorities,” she said.
Gamboa’s patient knows the cost of care all too well.
In 2015, the American College of Obstetricians and Gynecologists wrote a committee opinion paper noting that unauthorized or undocumented immigrants are less likely than other residents of the US to have health insurance.
The paper also noted that ACOG “supports a basic healthcare package for all women, without regard to immigration status, and helps achieve this by promoting universal access to health insurance for all individuals in the United States and advocating for the elimination of barriers to existing federal programs, including Medicaid”.