Small Intestine Cancer Survival Rates by Stage and Type

Survival rates for small intestine cancer range from under 20% to above 90% at five years, depending almost entirely on two things: the type of tumor and how far it has spread at diagnosis. Across all types combined, roughly six in ten people are alive five years after diagnosis, but that average obscures enormous variation between, say, a slow-growing neuroendocrine tumor caught early and an aggressive adenocarcinoma found after it has already reached the liver. Understanding what drives these differences matters, because small intestine cancer has been quietly increasing for decades, with cases more than doubling in the developed world over the past 40 years.¹

Why the Type of Tumor Matters More Than Almost Anything Else

The small intestine can develop several distinct cancer types, and they behave so differently from one another that lumping them together is almost misleading. A large U.S. population study covering 1992 to 2006 identified four main categories among nearly 11,000 cases: neuroendocrine cancers (the most common), carcinomas (adenocarcinomas and others), lymphomas, and sarcomas.² Five-year relative survival for neuroendocrine cancers in that study was about 81%, while for carcinomas it was only 28%. Lymphomas and sarcomas fell somewhere in between. Follicular B-cell lymphomas had the single best outcomes, exceeding 90% survival at five years, while a subgroup of poorly characterized carcinomas had the worst, with five-year survival around 21%.²

That spread, from roughly one in five to nine in ten, is far wider than what you see in most common cancers. The reason is partly biological: neuroendocrine tumors tend to grow slowly and may remain manageable for years even after spreading, while adenocarcinomas are often aggressive and diagnosed late. It is also partly a matter of how the tumors respond to treatment: some types are highly sensitive to chemotherapy or targeted drugs, while others have few effective systemic options.

Adenocarcinoma by Stage

Adenocarcinoma is the type most people mean when they talk about small bowel cancer, and it carries the most sobering numbers. Five-year survival has hovered around 35% for years, a figure that has proven stubbornly resistant to improvement compared with progress in colorectal cancer.¹ Stage is the strongest predictor of how long someone will live after diagnosis.

For stage I disease, where the tumor is confined to the intestinal wall, outcomes are relatively favorable, with five-year survival often exceeding the overall average by a wide margin. By stage III, when cancer has reached nearby lymph nodes, survival drops substantially. One large analysis found that patients with stage III adenocarcinoma who had surgery alone had a median survival of about 26 months, compared with about 42 months when adjuvant chemotherapy was added.³ Stage IV disease, where the cancer has spread to distant organs, carries the worst prognosis and was independently associated with poorer survival in multiple analyses.⁴

Where exactly in the small bowel the adenocarcinoma arises also plays a role, though a more modest one. Older data comparing duodenal tumors with those in the jejunum or ileum found corrected five-year survival rates of about 39% and 46%, respectively, a difference that did not reach statistical significance.⁵ More recent work suggests that tumors in a more proximal location (closer to the stomach) may carry worse survival, possibly because of differences in biology and in how aggressively nearby lymph nodes can be cleared during surgery.⁴

Neuroendocrine Tumors Have a Very Different Trajectory

Small intestinal neuroendocrine tumors, sometimes still called carcinoid tumors, are the most common malignancy in the small bowel and also the most survivable. Overall five-year survival sits around 72% to 80%, depending on the study and whether relative survival (adjusting for expected deaths in the general population) is used.⁶ Many patients live well over a decade, even some with metastatic disease, which distinguishes these tumors sharply from adenocarcinomas.

That said, not all neuroendocrine tumors are equally tame. The tumor’s proliferation rate, measured by a marker called Ki-67, is one of the strongest predictors of outcome. Tumors with a Ki-67 above 10% carried roughly five times the risk of death compared with the lowest-proliferation tumors in one large analysis.⁷ Stage also matters: patients with stage IV disease and a Ki-67 above 5% faced nearly four times the risk of death compared with those who had lower proliferation rates, while in earlier stages Ki-67 was less useful for distinguishing who would do well and who would not.⁸ In practical terms, most small intestinal neuroendocrine tumors grow so slowly that the standard grading tools used for other cancers lose some of their predictive power in the early stages.

Liver metastases are common in these tumors and represent a key fork in the road. When surgeons can remove at least 70% of liver metastases along with the abdominal disease, median overall survival can reach about 76 months. When liver metastases are left untreated, survival drops to roughly 20 to 22 months regardless of how well the abdominal disease is controlled.⁹ This is one of the clearest examples in small bowel oncology of aggressive surgery changing the survival clock.

Lymphoma Subtypes and Their Wide Range

Lymphomas of the small intestine are not a single disease. The most common subtype is diffuse large B-cell lymphoma, an aggressive but often chemotherapy-responsive tumor. Among patients with this subtype, five-year overall survival reached about 84% when they had favorable prognostic scores, dropping to roughly 47% with higher-risk features.¹⁰ The International Prognostic Index, which accounts for age, disease extent, and other clinical features, remains one of the best tools for estimating where an individual patient falls on that spectrum.

T-cell and natural killer cell lymphomas of the intestine are a different story. Five-year overall survival for these subtypes was only about 30% in one comparison study, versus roughly 74% for aggressive B-cell intestinal lymphomas.¹⁰ One particularly grim subtype is enteropathy-associated T-cell lymphoma, which is linked to celiac disease. U.S. data covering 2000 to 2018 showed that more than 80% of patients with this subtype died within five years, though those who received chemotherapy fared better than those who did not.¹¹ The takeaway is that the word “lymphoma” alone tells you almost nothing about prognosis here: B-cell versus T-cell, and indolent versus aggressive, are distinctions that separate excellent outcomes from very poor ones.

Gastrointestinal Stromal Tumors in the Small Bowel

Gastrointestinal stromal tumors, or GISTs, arise from specialized pacemaker-like cells in the gut wall. When they occur in the stomach, outcomes tend to be relatively good. Small bowel GISTs are more concerning: five-year disease-free survival for non-gastric GISTs was about 62% in one series, compared with 90% for gastric ones, a statistically significant difference.¹² Part of the reason is that small bowel GISTs tend to present at higher risk categories and are more prone to recurrence.

The introduction of targeted therapy with imatinib transformed GIST treatment across all sites. For small bowel GISTs specifically, the addition of systemic therapy to surgery increased over time and was associated with improved survival. In a period analysis comparing outcomes before and after broader imatinib adoption, adjusted survival was significantly better in the later era.¹³ Risk stratification systems that account for tumor size, location, and how quickly the cells are dividing remain central to deciding who benefits from prolonged targeted therapy after surgery.

Rare Sarcomas and Leiomyosarcoma

Before GISTs were recognized as a distinct entity, many smooth-muscle tumors of the gut were classified as leiomyosarcomas. True leiomyosarcoma of the small bowel is now understood to be quite rare, and it is often found at an advanced stage because symptoms are nonspecific. Surgery remains the only curative treatment.¹⁴

A larger SEER analysis of gastrointestinal leiomyosarcomas (not limited to the small bowel but including it) found that when patients underwent surgery, five-year cancer-specific survival was about 93% and overall survival about 85%. Without surgery, those figures dropped to roughly 79% and 61%, respectively. On deeper analysis, tumor grade and stage were the independent factors driving survival: high-grade tumors carried about eight times the risk of death compared with low-grade ones, and distant metastasis roughly tripled that risk.¹⁵

How Lymph Node Evaluation Affects Reported Survival

In small bowel adenocarcinoma, the number of lymph nodes a surgeon removes and a pathologist examines has a surprisingly large influence on survival statistics, and probably on actual outcomes too. For stage II disease (no lymph node involvement), five-year disease-specific survival ranged from 44% when zero nodes were assessed to 83% when more than seven nodes were checked.¹⁶ That gap is partly a staging effect: if few nodes are examined, some patients who truly have node-positive disease get classified as stage II and lower the apparent survival for that group. But there is also likely a therapeutic benefit to more thorough lymph node removal.

The ratio of positive to total lymph nodes examined, known as the lymph node ratio, is an even more powerful predictor than the raw count of involved nodes. One analysis found that median overall survival dropped from 71 months for patients with no positive nodes all the way to 16 months when more than 40% of examined nodes contained cancer.¹⁷ The practical implication is that the quality of surgery and pathologic examination has a direct bearing on both the accuracy of your staging and, possibly, on survival itself. Patients treated at higher-volume academic centers tend to have better survival, which may reflect more thorough surgical technique.⁴

Chemotherapy and When It Helps

For adenocarcinoma, the evidence supporting adjuvant chemotherapy after surgery is strongest in stage III disease. A large meta-analysis of studies covering over 6,400 patients found that adjuvant chemotherapy was associated with a roughly 40% reduction in the risk of death overall, and the benefit was most pronounced in stage III, where the risk reduction was about 45%.¹⁸ For stage II disease, the benefit was more modest and statistically borderline.

Digging further, not all stage II or stage III tumors benefit equally. A multicenter retrospective study found that adjuvant chemotherapy improved disease-free survival and overall survival in high-risk stage II tumors (those invading through the full bowel wall or with too few lymph nodes examined) and high-risk stage III tumors, but not in lower-risk subsets of those stages.¹⁹ For stage I disease, there was a numerical trend toward longer survival with chemotherapy, but it did not reach statistical significance.³ In practice, the decision about whether to add chemotherapy after surgery often comes down to where you fall within your stage: someone with a deeply invasive tumor and few lymph nodes examined stands to gain more than someone with a superficial tumor and a clean nodal harvest.

Immunotherapy in Tumors With Specific Molecular Features

A newer and potentially transformative development involves immune checkpoint inhibitors, but only for a subset of patients whose tumors have a feature called microsatellite instability. Small bowel adenocarcinomas have higher rates of this molecular feature than many other digestive cancers, which has made them a particular area of interest. In a multicenter study of patients with advanced digestive cancers showing microsatellite instability, those treated with immunotherapy had a two-year progression-free survival rate of about 71%, compared with roughly 8% for those who received standard chemotherapy. Response rates were also dramatically higher with immunotherapy: about 61% versus 26%.²⁰ The benefit was not limited to one tumor site and held regardless of where the primary cancer was located.

The catch is that only a fraction of small bowel cancers show microsatellite instability, and the testing is not always done reflexively the way it is for colorectal cancer. If you or someone you know is facing an advanced small bowel adenocarcinoma, confirming whether the tumor has this molecular signature is one of the most consequential tests available, because it opens the door to a class of drugs with dramatically different response rates.

Crohn’s Disease and Other Predisposing Conditions

Certain chronic conditions raise the risk of developing small bowel adenocarcinoma, and they can also affect survival after diagnosis. Crohn’s disease is the best-studied example. A Korean bicenter cohort study found that while overall survival between sporadic and Crohn’s-associated small bowel adenocarcinoma was statistically similar when all stages were pooled, patients with Crohn’s-associated disease had significantly worse survival when the cancer was diagnosed at an advanced stage. Crohn’s disease was an independent risk factor for death, roughly doubling the hazard.²¹

Crohn’s-associated tumors tend to occur in the ileum, which is less accessible to standard endoscopy, and they can be masked by inflammatory symptoms the patient has lived with for years. The result is that these cancers are often found later and at more advanced stages. Other conditions that raise small bowel cancer risk include familial adenomatous polyposis and Lynch syndrome, though evidence on whether these heritable syndromes independently change survival after diagnosis is thinner. Lynch syndrome is linked to microsatellite instability, which, as discussed above, may actually open better treatment options in the advanced setting.

Age, Treatment Setting, and Demographic Patterns

Across all types of small intestine cancer, age at diagnosis is one of the most consistent prognostic factors. People diagnosed before age 60 consistently survive longer than those diagnosed later, a pattern that holds across histologic subtypes.² The peak age for mortality from small intestine cancer falls in the 65-to-69 range.²² Older patients are more likely to have comorbidities that limit treatment options or increase surgical risk, which contributes to the survival gap.

Gender and race, by contrast, do not appear to drive large differences in survival once histology and stage are accounted for.² Where you are treated, however, does matter. Studies of small bowel adenocarcinoma have found that patients treated at academic cancer programs had better survival than those at community programs, even after adjusting for tumor characteristics and comorbidity.⁴ Given how uncommon these cancers are, the experience of the surgical and oncology team likely makes a meaningful difference in both the completeness of lymph node dissection and in choosing the right systemic therapy.

Why These Numbers Are Harder to Pin Down Than for Common Cancers

Small intestine cancer accounts for only a small fraction of all gastrointestinal malignancies, which means the evidence base is thinner than what exists for stomach, colon, or pancreatic cancer. Many of the survival estimates come from retrospective database analyses rather than prospective randomized trials, and the numbers can shift depending on the time period studied, the country, and whether relative or absolute survival is reported. A five-year survival figure of 60% drawn from a U.S. population database includes patients diagnosed across many years and treated with varying approaches, some of which have since been superseded.

The rarity also means that most oncologists will see only a handful of cases in a career, and treatment protocols are frequently adapted from evidence in colorectal cancer rather than generated from dedicated small bowel trials. Ongoing research, particularly in molecular profiling and immunotherapy, is beginning to change this, but it is worth knowing that the survival numbers available today reflect a mix of historical and contemporary treatment and will likely improve as more targeted approaches become standard.

1
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2
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3
PubMed. Efficacy of adjuvant chemotherapy for small bowel adenocarcinoma: A propensity score-matched analysis
4
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PubMed. Survival in small intestinal adenocarcinoma
6
PubMed. Small intestinal neuroendocrine tumors: prognostic factors and survival
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8
The American Journal of Surgical Pathology. The Influence of Tumor Stage on the Prognostic Value of Ki-67 Index and Mitotic Count in Small Intestinal Neuroendocrine Tumors
9
PubMed. Outcomes of cytoreductive operations for peritoneal carcinomatosis with or without liver cytoreduction in patients with small bowel neuroendocrine tumors
10
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11
PubMed. Patients with enteropathy-associated T-cell lymphoma in the United States from 2000 to 2018: SEER data-base analysis
12
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13
PubMed. The Impact of Imatinib on Survival and Treatment Trends for Small Bowel and Colorectal Gastrointestinal Stromal Tumors
14
PubMed Central. Leiomyosarcoma of the small bowel: A case report and literature review
15
PubMed Central. Prognostic Factors in Gastrointestinal Leiomyosarcomas: An Analysis Using the Surveillance, Epidemiology, and End Results (SEER) Database
16
PubMed. Prognostic value of lymph node evaluation in small bowel adenocarcinoma: analysis of the surveillance, epidemiology, and end results database
17
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18
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PubMed. A multicenter study evaluating efficacy of immune checkpoint inhibitors in advanced non-colorectal digestive cancers with microsatellite instability
21
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