Rates of breast cancer and cervical cancer have increased by 13% and 14% in women under 50 over the past 20 years. Photo / 123RF
Cancer is affecting increasing numbers of young women, and the hormone oestrogen is thought to play a central role.
As an NHS oncologist who treats breast cancer patients, Dr Saif Ahmad and his colleagues have noticed an alarming trend in recent years. While breast cancer is still a disease which predominantly affects older women, with the highest incidence of cases in 65 to 69-year-olds according to Cancer Research UK (CRUK), Ahmad and his team have found themselves seeing increasing numbers of patients in their 20s, 30s and 40s.
“We’ve certainly felt like there are more younger women presenting with breast cancer,” says Ahmad, an academic consultant in clinical oncology at the University of Cambridge. “These are women who in some cases are recently married, have young children, or are even presenting with cancer while pregnant, which can lead to huge challenges regarding what to do about the baby.”
This trend is starting to become apparent at a population level scale, for a number of cancers. CRUK researchers told The Telegraph rates of breast cancer and cervical cancer have increased by 13% and 14% in women under 50 over the past 20 years. The rate of increase is even greater in other forms of cancer, with the numbers of 25 to 49-year-olds with thyroid, small intestine and kidney cancers increasing by 231%, 119% and 96% over the past decade alone, although the overall case numbers are still relatively low in this age group.
It also appears younger women are becoming more vulnerable to developing cancer than younger men. According to the American Cancer Society, cancer rates in women under the age of 50 are 82% greater than for their male counterparts. In 2002, that same statistic was 51%.
Having observed this worrying pattern in his own patients, Dr Siddhartha Yadav, an oncologist at the Mayo Clinic Comprehensive Cancer Centre in Rochester, Minnesota, and others have established a research project specifically aimed at understanding more about young-onset cancers.
Yadav says one of the most alarming aspects about this trend is that these cancers often tend to be diagnosed at a higher stage and grade, which means they’re more likely to spread. They also appear to be more aggressive diseases.
“One of the key worries is that the patients aren’t often aware that they are at risk, and they haven’t received the kinds of surveillance testing we do in older women, so they get diagnosed later,” says Yadav. “It’s also possible that the biology of young-onset cancers may be different to those of older patients. The tumour characteristics appear to be quite different.”
But oncologists still have no clear explanation for why more younger women are developing cancer, a question which ongoing research projects are urgently looking to address. For now, we only have a number of theories, many of which relate to the female sex hormone, oestrogen.
Two years ago, a study from Harvard scientists found that oestrogen may play a far more central role in breast cancer than previously thought, potentially contributing to as many as a third of all cases.
Oestrogen has long been seen as a catalyst for various cancers, particularly forms of breast, ovarian and endometrial cancer, because it stimulates the division and proliferation of breast tissue, a process that carries the risk for cancer-causing mutations. However, the Harvard study indicated that oestrogen can also cause direct changes to the DNA of cells, making them more prone to becoming cancerous.
Because of this, various factors that increase exposure to oestrogen, are thought to elevate cancer risk.
Yadav points to rising obesity levels as a possible driver of young-onset cancers, because excess fat increases the amount of oestrogen in the bloodstream.
Another possible cause is the progressively declining age of menarche – the scientific term for when girls begin menstruation. Last year, a study in the journal JAMA found that increasing numbers of girls under the age of 12 are beginning menstruating.
“If you start your period earlier, then you’re exposed to oestrogen for longer,” says Ahmad.
Yadav suggests changing patterns of reproductive behaviour may also be playing a role, with more women choosing to either have children later in their 30s and 40s, or not at all, compared with previous generations. Because childbirth interrupts the normal oestrogen cycle, with levels dropping for several weeks, it is thought to act as something of a reprieve for the body.
“We’ve known that women who don’t have kids are at an increased longer-term risk of breast and other cancers, and this is thought to be due to how pregnancy changes the levels of hormones like oestrogen and progesterone,” says Yadav.
But scientists emphasise the reasons behind this trend are likely to be multifactorial, and it will likely take a combination of artificial intelligence and vast datasets to really pinpoint the major causes of these young-onset cancers.
Yadav points to how changing dietary patterns, with increasing consumption of ultra-processed foods, may be altering the microbiome of some women, which in turn could be impacting their immune system’s ability to detect and destroy cancer cells before they proliferate. Other oncologists suspect that other lifestyle changes may also be responsible.
Dr Larry Norton, a breast medical oncologist at Memorial Sloan Kettering Cancer Centre in New York, says there is some evidence that changing sleeping behaviour, either through women getting poorer quality sleep or less regular sleep patterns could be altering hormonal pathways, increasing their risk of breast cancer.
According to Ahmad, many of the key warning signs of these cancers are the same at any age, for example the appearance of lumps or a change in the appearance of the breast, or abdominal pain, nausea, vomiting or dark-coloured stools in the case of small intestine cancer.
“If there’s any major concern, we tend to advise women to reach out to their GP, so the general advice is to be mindful, and in the case of breast cancer, self-examination of the breasts on a monthly basis, is not necessarily a bad thing to do,” he says.
For cervical cancer, warning signs can range from unusual pain during sex, bleeding between periods or after sex, to vaginal discharges which can appear watery and have a strong odour or contain blood.
The NHS lists warning signs of thyroid cancer as being a painless, hard lump in the front of the neck which is slowly growing in size, hoarseness or other changes to the voice, pain in the front of the neck which extends to the ears, and swollen lymph glands which seem to be getting larger.
How should a breast self-exam be performed?
In the shower
Check for: Lumps, thickening, hardened knot, any other breast changes.
In front of a mirror
Check for: Dimpling, puckering, changes to one side.
Lying down
Check for: Discharge, lumps.
While breastfeeding is generally recommended if possible, Dr Ahmad points out it actually plays a little-known protective role when it comes to cancer risk.
“The tissue within the breast is regularly remodelled to produce milk for a child,” he says. “It’s a kind of reset and when that happens, there’s some theories which suggest that this process helps to shed and get rid of early microscopic cancer cells as well.”
As well as focusing on general healthy lifestyle habits such as regular sleep, exercise, minimising alcohol intake and eating a balanced diet, Norton recommends knowing your family history as much as possible.
“If you don’t know your family history, it’s a good idea to ask some questions, and find out if there’s any likely genetic predisposition for a particular form of cancer so you can get tested,” he says. “There’s a lot of people walking around with abnormal genes that they inherited from their mother or father that predispose them to illnesses including breast cancer, and knowing about that can help you make some choices. For example, women in their 20s and 30s who are at higher risk of breast cancer based on their family history, may want to consider getting an MRI as well as a mammogram to pick things up before they develop.”
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