Marisa Peters had been experiencing symptoms for years: blood on her toilet paper after going to the bathroom, changes in her stool and difficulty controlling the urge to poop. But she was in her 30s, healthy and physically active. She did not have any abdominal pain, and doctors dismissed the symptoms as hemorrhoids, or normal postpartum changes after the birth of her first son. When Ms. Peters finally visited a gastroenterologist in 2021, after having her third child and experiencing worsening bleeding from her rectum along with changes in her stool consistency, an urgent colonoscopy confirmed that she had colorectal cancer.
玛丽莎·彼得斯多年来一直有这些症状：上完厕所后卫生纸上有血迹，大便发生变化，以及难以控制排便的冲动。但她才30多岁，身体健康，喜欢运动。她没有腹痛，医生认为是痔疮导致她的那些症状，或者是生完第一个儿子后的正常产后变化。2021年，在生了第三个孩子后，彼得斯终于去看了肠胃科医生，当时她的直肠出血的情况变严重了，大便粘稠度也发生了变化，紧急结肠镜检查证实她患有结直肠癌。

It had been four or five years since her symptoms had first emerged. Yet “I did not expect that cancer was going to be what they found,” Ms. Peters said.
此时距离她第一次出现症状已经过去了四五年。彼得斯说，然而，“我没料到会是癌症。”

A report published by the American Cancer Society in January suggests that rates of colorectal cancer are rising rapidly among people in their 20s, 30s and 40s — even as incidence is declining in people over the age of 65.
美国癌症学会今年1月发布的一份报告显示，在20、30、40多岁的人群中，结直肠癌发病率正在迅速上升，而65岁以上人群的发病率却在下降。

“It’s unfortunately becoming a bigger problem every year,” said Dr. Michael Cecchini, a co-director of the colorectal program in the Center for Gastrointestinal Cancers and a medical oncologist at Yale Cancer Center. He added that early-onset colorectal cancers have been increasing by about 2 percent per year since the mid-1990s. This increase has moved colorectal cancer up to being the top cause of cancer deaths in men under the age of 50 and the second-leading cause of cancer deaths in women under 50 in the United States.
耶鲁大学癌症中心的肿瘤学专家、该中心下设胃肠道癌症中心结直肠项目联合主任迈克尔·切基尼博士表示，“很遗憾，这个问题一年比一年严重。”他还说，自1990年代中期以来，早发性结直肠癌每年增加约2%，这使得结直肠癌成为美国50岁以下男性癌症死亡的首要原因，也是50岁以下女性癌症死亡的第二大原因。

In fact, experts are noticing a rise in early-onset colorectal cancers around the world — a trend that they are racing to explain.
事实上，专家们注意到世界各地早发性结直肠癌的发病率都在上升，他们正在努力解释这一趋势。

Why is colorectal cancer increasing among young people? 为什么结直肠癌在年轻人中越来越多?

Colon and rectal cancers share many similarities and are typically lumped into one category, called colorectal cancer. Studies, however, show that the increase in diagnoses is mainly driven by a rise in rectal cancers and cancers found in the left, or distal, side of the colon, near the rectum. “That maybe provides an important clue for understanding what might be going on,” said Caitlin Murphy, an associate professor and cancer researcher at UTHealth Houston.
结肠癌和直肠癌有许多相似之处，通常被归为一类，称为结直肠癌。诊断率上升主要是由于直肠癌和结肠左侧，也就是结肠末端靠近直肠附近的癌症增加引起的。“这也许为了解究竟是怎么回事提供了一个重要线索，”休斯顿得克萨斯大学医学中心的副教授、癌症研究员凯特琳·墨菲说。

Colorectal cancers in younger people also tend to be more aggressive, and they are often found at a more advanced stage, Dr. Murphy said. But most people affected by early-onset colorectal cancer are too young to be recommended for routine cancer screenings, which have helped decrease rates in adults over 50. In 2021, the U.S. Preventive Services Task Force reduced the recommended age for starting colorectal cancer screening by just five years — from 50 to 45.
墨菲说，年轻人的结直肠癌往往更具侵袭性，而且往往较晚才被发现。但大多数患早发性结直肠癌的人都太年轻，不符合常规癌症筛查的推荐年龄，这种筛查已经帮助降低了50岁以上成年人的癌症发病率。2021年，美国预防服务工作组将结直肠癌筛查的推荐年龄从50岁降至45岁，仅降低5岁。

A vast majority of colorectal cancer diagnoses are still made in people 50 and older. The American Cancer Society predicted last year that roughly 153,000 new diagnoses would be made in the U.S. in 2023, of which 19,550 would be in people younger than 50. But millennials born around 1990 now have twice the risk of colon cancer compared with people born around the 1950s, while millennials’ risk for rectal cancer is about four times higher than that of older age groups, according to a study published in the Journal of the National Cancer Institute. That means diagnoses are likely to “continue going up as these higher-risk generations age,” Dr. Murphy said.
绝大多数结直肠癌的诊断仍然发生在50岁及以上的人群中。美国癌症学会去年预测，2023年美国将有大约15.3万例新确诊病例，其中19550例患者年龄在50岁以下。但根据发表在《国家癌症研究所杂志》上的一项研究，1990年左右出生的千禧一代患结肠癌的风险是20世纪50年代左右出生者的两倍，而千禧一代患直肠癌的风险是年龄较大的人群的四倍。墨菲说，这意味着“随着高危人群年龄的增长”，确诊病例可能还会继续增加。

When cancer is found at a younger-than-usual age, doctors usually suspect that genetic mutations may be to blame. And some molecular studies suggest that tumors in early-onset colorectal cancers do have different mutations driving the cancer compared with tumors in older adults. Another piece of evidence that there is a genetic component: It is clear that having a first-degree relative who had colorectal cancer — or even a precancerous polyp — can increase your risk, Dr. Cecchini said. But genetic changes do not explain the full picture, he said.
当发现癌症的年龄小于正常年龄时，医生通常会怀疑基因突变可能是罪魁祸首。而一些分子研究表明，与老年人的肿瘤相比，早发性结直肠癌的肿瘤确实有不同的突变驱动因素。另一个证据表明，这也与遗传因素有关：切基尼说，很明显，直系亲属患有结直肠癌——甚至是癌前息肉——可能会增加你的患癌风险。但他说，基因变化并不能解释全部情况。

Some research has linked lifestyle and dietary changes to increased rates of colorectal cancer in both young people and older adults. Recent generations have consumed more red meat, ultraprocessed foods and sugary beverages, and have been known to binge drink more frequently; between 1992 and 1998, cigarette smoking also increased before declining again, while physical activity has continuously declined for decades. All of these factors — along with the rise in obesity rates since the 1980s — are associated with cancer risk. But once again, none of them fully account for the increase in early-onset colorectal cancer.
一些研究将生活方式、饮食变化与年轻人和年龄更大的人当中患结直肠癌的增加联系起来。近几代人消费了更多红肉、精加工食品和含糖饮料，并且更频繁地饮酒；在1992年至1998年间，吸烟也增加了，然后再次下降，而体育锻炼在过去几十年里持续减少。所有这些因素——以及自上世纪80年代以来肥胖率的上升——都与癌症风险有关。然而，再一次强调，这些因素并不能完全解释早发性结直肠癌的增加。

“For a lot of these risk factors, like smoking, you have to be exposed for long periods of time before the cancer develops,” said Dr. Andrea Cercek, a co-director of the Center for Young Onset Colorectal and Gastrointestinal Cancers at Memorial Sloan Kettering Cancer Center. And many patients in their 20s and 30s do not even fit in these risk groups, she said. “Many of our patients are athletes,” she said. “Many of them were never heavy, not even in childhood.”
纪念斯隆-凯特林癌症中心下设的早发性结直肠癌和胃肠道癌症中心联席主任安德烈亚·塞切克博士说，“对于很多风险因素，比如吸烟，你必须在长时间暴露后才能发展成癌症。”许多二三十岁的患者甚至不属于这些风险群体。“我们的很多病人都喜欢运动，”她说。“他们中的许多人从来都不胖，甚至在小时候也不胖。”

Experts are beginning to investigate if there are other environmental drivers of early-onset cancer. For instance, some small studies have hinted at the idea that people who develop colorectal cancer at an early age have an imbalance of “good” and “bad” bacteria in their gut. Researchers are not only looking at antibiotic use, which can alter the gut microbiome, but also nonsteroidal anti-inflammatory drugs that are used as painkillers, proton pump inhibitors that are used to counter stomach acid issues and several psychiatric medications that may be absorbed through the intestinal lining and have increased in use in recent decades, Dr. Cercek said.
专家们开始调查早发性癌症是否还存在其他环境驱动因素。例如，一些小型研究揭示出早年患结直肠癌的人肠道中的“好”细菌和“坏”细菌不均衡。塞切克说，研究人员不仅关注可能改变肠道微生物群的抗生素使用情况，而且还关注了用作止痛药的非甾体抗炎药、用于解决胃酸问题的质子泵抑制剂，以及一些可能通过肠道内壁吸收的精神科药物，这些药物的使用在近几十年来有所增加。

Some experts believe exposure to toxic chemicals in the environment may also be to blame. “There’s patterns of environmental exposures by geography, by race, by sex, by all the things that we know colorectal cancer rates also differ by,” Dr. Murphy said.
一些专家认为，接触环境中有毒的化学物质也可能是罪魁祸首。“我们知道结直肠癌发病率也与地理位置、种族、性别等因素决定的环境暴露模式相关，”墨菲说。

For instance, for many years, the rates of colorectal cancer diagnoses were highest among non-Hispanic Black people, but research shows that these cancers increased more among non-Hispanic white people in the 1990s and early 2000s, Dr. Murphy said. Now, both groups have fairly similar rates of cancer. “Does this mean that white people are now being exposed to something that Black people have been exposed to for many, many years? We just don’t know yet,” Dr. Murphy said.
例如，墨菲说，非西班牙裔黑人在相当长一段时间里一直有着最高的结直肠癌率，但研究表明，在20世纪90年代和21世纪初，这些癌症在非西班牙裔白人中的上升幅度更大。现在，这两个群体的发病率大致相当。“这是否意味着白人现在正在接触到黑人已经接触了很多很多年的东西？我们尚不清楚，”墨菲说。

There are also geographic disparities in the increase in cancer, with experts seeing more cases emerge in cities and towns along the Mississippi River, in Southeastern states and in Appalachia, which may be explained by occupational exposures to trace elements like arsenic, chromium, and nickel, which are often used in coal production, chemical plants and other industries in those regions. So-called forever chemicals like per- and polyfluoroalkyl substances, better known as PFAS, have been linked to other cancers and could also be driving some of the increase in early-onset colorectal cancer.
癌症发病率的增加也存在地域差异，专家发现，密西西比河沿岸、东南部各州和阿巴拉契亚地区的城镇出现了更多病例，这可能是由于这些地区的煤炭生产、化工厂和其他行业经常使用砷、铬和镍等微量元素，从而导致了职业接触。全氟烷基和多氟烷基物质（更广为人知的名称是PFAS）等所谓永久化学物质与其他癌症有关，也有可能导致早发性结直肠癌的增加。

“I don’t think there’s going to be one smoking gun that explains everything,” Dr. Murphy said. “It’s a whole bunch of things.”
“我不认为有一个确凿的证据可以解释一切，”墨菲说。“是很多东西的集合。”

What can you do to identify and reduce your risk?
如何识别和降低风险？

After Ms. Peters was diagnosed and started chemotherapy, radiation, and reconstructive surgery, she encouraged her younger sister and brother to get screened immediately. “Because now they had a family history of the disease,” she said.
在彼得斯被确诊并开始化疗、放疗和重建手术后，她鼓励妹妹和弟弟立即接受筛查。“因为现在他们有了这种疾病的家族史，”她说。

The Colon Cancer Coalition has developed a script you can use to bring up colon and rectal cancer questions in conversations with relatives, which may help you determine whether you should be screened 10 to 15 years earlier than the current recommended age.
结肠癌联盟开发了一个脚本，你可以使用它在与亲属交谈时提出结肠癌和直肠癌的问题，它可以帮助你决定是否应该比目前推荐的年龄提早10到15年进行筛查。

If you are not in contact with your immediate family or are unaware of their medical history, it is important to know the symptoms of colorectal cancer, such as unexplained abdominal pain, changes in your stool and rectal bleeding. If you have any of these symptoms, talk to a doctor and get tested to rule out cancer.
如果你与直系亲属没有联系，或不知道他们的病史，那么了解结直肠癌的症状是很重要的，比如无法解释的腹痛、大便变化和直肠出血。如果你有这些症状，请咨询医生并接受检查以排除癌症。

After her experience being dismissed by doctors, Ms. Peters founded an organization called Be Seen to raise awareness of symptoms and encourage people to pledge to be screened.
经历了被医生忽视之后，彼得斯成立了一个名为“被看到”的组织，以提高人们对症状的认识，并鼓励人们承诺接受筛查。

Colonoscopies remain the gold standard for screening because they allow medical experts to not only see where tumors are, but also to remove them in the same procedure. There are now several different ways patients can prepare their bowels — including liquid laxatives, pills and powders — that are not as uncomfortable as options that were available to previous generations. “I can promise you that doing a one-day cleanse to prep for a colonoscopy is far better than having poop coming out of your stomach into a bag,” Ms. Peters said. “Thankfully, it was temporary for me, but it’s not for many people.”
结肠镜检查仍然是筛查的黄金标准，因为它不仅可以让医学专家看到肿瘤的位置，还可以在操作中顺便切除肿瘤。患者可以通过几种不同的方法来准备清空肠道——包括液体泻药，药丸和粉末——这些方法不像前几代方式那样让人不舒服。“我可以向你保证，为结肠镜检查做前一天的清肠准备，远比把大便从胃里排进粪袋要好，”彼得斯说。“谢天谢地，粪袋对我来说是暂时的，但对很多人来说不是。”

There is also a home test that can detect 92 percent of colorectal cancers through DNA in your stool, though it is less sensitive at picking up precancerous polyps and cannot be used to remove any tissue, Dr. Cercek said. A blood test that is on the horizon may further increase the number of people willing to get screened.
塞切克说，还有一种居家检测，可以通过粪便中的DNA测出92%的结直肠癌，不过这种方法在检测癌前息肉方面不太敏感，也不能用于切除任何组织。即将推出的血液检测可能会进一步增加愿意接受筛查的人数。

Even though the trend in early-onset colorectal cancers is concerning, “what I take away from it is that the time to intervene is even earlier,” Dr. Murphy said. “And certainly what is happening now is going to affect the health of generations many, many years from now.”
尽管早发结直肠癌的趋势令人担忧，但是，“我从中能看到的是，干预的时间进一步提前了，”墨菲说。“现在发生的一切肯定会影响很多很多年后几代人的健康。”

本文最初发表于2024年3月27日。

Knvul Sheikh是《纽约时报》记者，报道慢性病、传染病以及其他个人健康方面的内容。

翻译：杜然、晋其角