{"id":348331,"date":"2026-03-26T05:42:08","date_gmt":"2026-03-26T05:42:08","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/348331\/"},"modified":"2026-03-26T05:42:08","modified_gmt":"2026-03-26T05:42:08","slug":"colorectal-cancer-what-are-the-symptoms-and-why-are-cases-in-younger-new-zealanders-rising","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/348331\/","title":{"rendered":"Colorectal cancer: What are the symptoms and why are cases in younger New Zealanders rising?"},"content":{"rendered":"

Experts are calling for the eligibility age for free bowel screening to be lowered to 45. This month the age is being lowered to 58<\/a> from 60 across the rest of the North Island after this was done in Northland, Auckland and the South Island in October.<\/p>\n

What are the signs and symptoms of colorectal cancer?<\/p>\n

Colorectal cancer is the clinical term for cancer of the colon or rectum, commonly known as bowel cancer.<\/p>\n

Symptoms can include rectal bleeding, anaemia, severe abdominal pain, a lump in the abdomen, changes in bowel movements, fatigue or weight loss for no apparent reason.<\/p>\n

\u201cEarly-onset cancer tends to be a left-sided disease, which means it tends to affect the rectum and the sigmoid [colon],\u201d colorectal surgeon Dr Frank Frizelle says. <\/p>\n

\u201cTumours in the rectum and sigmoid are more likely to present with rectal bleeding and increased rectal mucus and increase in frequency of defecation, which is associated with almost normal stool. <\/p>\n

\u201cRight-sided tumours tend to present more subtly \u2013 with anaemia, fatigue, a lump in the tummy, loose stool as opposed to formed stool and not so much overt rectal bleeding.\u201d <\/p>\n

What causes colorectal cancer?<\/p>\n

Frizelle says about 1% of bowel cancer is associated with chronic inflammatory diseases like ulcerative colitis or Crohn\u2019s disease.<\/p>\n

\u201cAbout 10% of people have an inherited genetic condition that increases their chance of getting bowel cancer. In younger people it accounts for a higher percentage, because if you\u2019ve got an inherited genetic condition, you tend to get bowel cancer at an early age.\u201d<\/p>\n

These conditions are related to mismatch repair gene abnormalities like Lynch syndrome, or FAP (familial adenomatous polyposis)<\/a> \u2013 genetic mutations that lead to cancer developing.<\/p>\n

Most bowel cancer \u2013 90% \u2013 is sporadic. \u201cIt just happens. That is largely driven by environmental conditions \u2013 the combination of the bacteria in your gut and the food you eat.\u201d<\/p>\n

What role do gut bacteria and diet play?<\/p>\n

Your gut bacteria is mostly inherited from your mother, and interacts with what you eat. Some types of gut bacteria produce toxins that damage cells and produce pre-cancerous lesions.<\/p>\n

One of these bacteria, Enterotoxigenic Bacteroides fragilis, makes \u201cmore toxin in the presence of red meat and less toxin in the presence of fibre and vegetables\u201d, Frizelle says.<\/p>\n

\u201cThat fits with what we know epidemiologically, that people who eat a lot of red meat are more likely to get bowel cancer. <\/p>\n

\u201cSo what we think causes sporadic bowel cancer is related to your diet and having certain bacteria in your gut that make toxins. Those are controlled by what happens in the early part of life.\u201d<\/p>\n

Your gut bacteria can change with your environment and diet at an early age, he says. For example, if you migrate as a teenager from a low-risk to a high-risk Western environment and diet, or from a rural to an urban setting, your gut bacteria changes for the worse.<\/p>\n

\u201cThat\u2019s not unlike what we know about sun damage in skin. It\u2019s not when you\u2019re 60 and get your sunburnt nose that causes your skin cancer, it\u2019s when you were 16 and got out there and got sunburnt, and it\u2019s 50 years later that the cumulative injury has occurred.\u201d<\/p>\n

What can increase or decrease your risk of getting colorectal cancer?<\/p>\n

Risk factors for colorectal cancer include being 50 or older, a family history of bowel cancer, eating too much red and processed meats and animal fats, and not getting enough fruit and vegetable fibre.<\/p>\n

Alcohol, smoking, obesity and a lack of exercise also increase your risk.<\/p>\n

You can lower your risk by eating a healthy diet, reducing fat and saturated fat intake, limiting red and processed meats, and exercising regularly.<\/p>\n

Why are cases rising among younger people in New Zealand?<\/p>\n

Research is being done to work this out, Frizelle says.<\/p>\n

\u201cIf our model is right, the bacteria is lying inside you and then the food\u2019s coming in, making toxins, causing damage.\u201d<\/p>\n

However, young people today eat less red meat and more vegetables, and drink and smoke at lower rates than in previous decades.<\/p>\n

\u201cSomething else environmental is altering the balance and causing something to change.\u201d<\/p>\n

The colon has a protective mucus layer that stops toxins from doing damage. It may be that processed foods, sugary drinks or microplastics are damaging it, Frizelle says.<\/p>\n

\u201cNot that the plastics themselves are causing the cancer, but they may damage the mucus layer or work as an agent to carry the toxins.<\/p>\n

\u201cWhy things have changed we don\u2019t know \u2013 we know it\u2019s environmental, what it is in the environment we don\u2019t know.”<\/p>\n

While bowel cancer cases are increasing in over-50s<\/a>, they have stayed the same in the 80-and-over age group. In the 60-80 age group, they are decreasing.<\/p>\n

\u201c[This is] largely due to screening, a lot of people having colonoscopies for rectal bleeding, and increased awareness,\u201d Frizelle says.<\/p>\n

\u201cIt\u2019s not that people 60 to 80 are leading a better life, it\u2019s just that they\u2019ve got a high level of intervention.\u201d<\/p>\n

For a third of people under 50 with bowel cancer, the disease is incurable by the time they present to a doctor. That can be because they don\u2019t recognise they have a problem, because symptoms can come and go. <\/p>\n

\u201cIt means there\u2019s a delay in patients recognising that they\u2019re not well. Secondly, the health structure is inevitably difficult to get through. GPs and the public system are focused on looking for [this in] older people.<\/p>\n

\u201cSo if you\u2019re 65 and have got rectal bleeding, you pretty much go to the front of the queue because they\u2019ll think it\u2019s rectal cancer. If you\u2019re 35 and have rectal bleeding, they\u2019ll say \u2018It\u2019s haemorrhoids, go away\u2019.\u201d<\/p>\n

What treatments are available in New Zealand?<\/p>\n

Treatment depends on the stage and site of the cancer. Early-stage cancers can be removed via a colonoscopy or excised via the rectum. <\/p>\n

\u201cIf it\u2019s a bit bigger, it involves surgery to resect the tumour. And if it\u2019s a bit more advanced than that, then you may need chemotherapy as well. If it\u2019s in your rectum and it\u2019s a locally advanced tumour, you\u2019ll get radiation and chemotherapy prior to surgery.\u201d <\/p>\n

Bethany Reitsma is a lifestyle writer who has been with the NZ Herald since 2019. She specialises in all things health and wellbeing and is passionate about telling Kiwis\u2019 real-life stories.<\/p>\n","protected":false},"excerpt":{"rendered":"Experts are calling for the eligibility age for free bowel screening to be lowered to 45. This month…\n","protected":false},"author":2,"featured_media":348332,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[52173,169841,95,192,36334,2534,2512,28403,797,24392,71,134,78,130,117,111,139,69,384,801,12072,131,223,2846,8238,6923,4276,1533,102,379,28028,80,24750],"class_list":["post-348331","post","type-post","status-publish","format-standard","has-post-thumbnail","category-health","tag-52173","tag-169841","tag-and","tag-are","tag-bowel","tag-cancer","tag-cases","tag-colorectal","tag-diagnosed","tag-each","tag-from","tag-health","tag-in","tag-more","tag-new","tag-new-zealand","tag-newzealand","tag-nz","tag-people","tag-rising","tag-symptoms","tag-than","tag-the","tag-them","tag-under","tag-what","tag-why","tag-will","tag-with","tag-year","tag-younger","tag-zealand","tag-zealanders"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/348331","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=348331"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/348331\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/348332"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=348331"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=348331"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=348331"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}