Simple appendectomy is a safe and effective surgical approach for low-grade appendiceal mucinous neoplasm at the appendiceal root with negative margins: a retrospective comparative cohort study

Abstract

Background

Appendiceal tumors are very rare among gastrointestinal tumors. Based on low-grade appendiceal mucinous neoplasm (LAMN) unique biological behavior and clinical characteristics, we hope to evaluate the safe surgical approach for LAMN at the root of the appendix.

Method

Collect and review the anthropological data of patients from January 1, 2013 to January 1, 2025. The patients were grouped according to different surgical methods, and the demographic data, anthropological characteristics, treatment plans and prognosis of the patients were compared and analyzed.

Result

A total of 97 patients were included in this study. Among them, 54 patients underwent simple appendectomy(SA), and 43 patients were in extended surgical resection (ESR) group (including partial cecectomy, ileocecal resection, right hemicolectomy, etc.). The average [SD] age in the SA group was 54.14[15.7] years, with 35 females [64.8%]. The incidence of postoperative complications in the SA group was 11.1%, which was significantly lower than 27.9% in ESR group, with a statistically significant difference (P = 0.040); however, there was no significant difference in the distribution of complication severity between the two groups. In addition, patients in the SA group achieved more rapid postoperative recovery. Following the exclusion of patients who had positive margins or tumor perforation, survival analysis results showed that there were no statistically significant differences in 5-year and 10-year overall survival (OS) rates or 5-year and 10-year recurrence-free survival (RFS) rates between the two groups.

Conclusion

For patients with LAMN at the root of the appendix, simple appendectomy is a safe and effective surgical approach.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-026-04206-9.

Introduction

Appendiceal tumors are very rare among digestive tract tumors, accounting for approximately 0.2% to 0.5% of digestive tract tumors [1, 2]. It is estimated that the annual incidence rate of appendiceal tumors is 0.12 per million people, but according to some large database studies, the incidence rate may be as high as 0.97 per 100,000 people [3]. Appendiceal tumors are mostly discovered in pathological examinations after appendectomy. Occasional appendectomy tumors account for approximately 0.2%−2% of pathological specimens after appendectomy [4–6].

Unlike most aggressive malignant tumors, Low-grade appendiceal mucinous neoplasm is characterized by mucinous epithelial hyperplasia accompanied by extracellular mucus and promoting the tumor margin. LAMN grows slowly, is inert and easily accessible, but lymph node metastasis and extraperitoneal spread are rare. However, mucus deposition may lead to the development of pseudomyxoma peritonei. Previous studies have shown that the diffusion of LAMN to the peritoneum and other parts can lead to the occurrence of Pseudomyxoma Peritonei (PMP) [7, 8]. Surgical treatment is currently recognized as the first choice for LAMN, and other adjuvant treatments after surgery are also feasible [9]. However, the extent of resection, such as appendectomy, ileotomy, and right hemicolectomy, is controversial [10, 11].

Although the disease progression of patients with LAMN-related PMP is slow, it is incurable and has a high recurrence rate, incidence rate and mortality rate. The reported 5-year and 10-year survival rates are 50–86% and 45–68%, respectively [12, 13]. Due to the rarity and indolence of LAMN, the classification of appendiceal tumors is controversial [14, 15]. Currently, there is a lack of guidelines and expert consensus for the diagnosis and treatment of LAMN. Therefore, many problems that need to be solved urgently have emerged in clinical practice, such as how to give reasonable staging based on clinicopathological indicators, how to determine the relatively optimal surgical range for different patients [16], and how to achieve better short-term and long-term effects by combining cell reduction surgery (CRS) with intraperitoneal hyperthermia chemotherapy (HIPEC) [17–20]. And currently, there are no studies on this particular clinical type of LAMN at the root of the appendix. Therefore, this retrospective study aims to explore the impact of simple appendectomy on the short-term and long-term clinical prognosis of patients with mucinous tumors at the root of the appendix.

Method

We searched the databases of Beijing Hospital and the Affiliated Hospital of Qingdao University to search for the clinicopathological records of LAMN patients undergoing consecutive series of surgeries from January 1, 2013 to January 1, 2025. The research procedure was approved by the Institutional Review Board and was conducted in accordance with the ethical standards of the Declaration of Helsinki in 1975. The pathological results of the patients were analyzed by two senior pathologists to determine the tumor location, and the pathological type and stage were further determined according to the eighth edition of the American Joint Committee on Cancer (AJCC). Inclusion criteria: The pathological type was LAMN, the tumor was located at the root of the appendix, and there was no abdominal or distant metastasis. Exclusion criteria: (1) Having a history of other types of malignant tumors within the past 5 years (excluding treated basal cell carcinoma of the skin, cervical intraepithelial neoplasia or localized prostate cancer). (2) Tumors in other parts were present at the time of admission for treatment. (3) No radical surgery or tumor biopsy was performed. (4) Lost to follow-up, survival date unknown. (5) Other malignant tumors were found during the follow-up period. (6) The postoperative survival time was less than one month. Collect and analyze clinical data. All patients were closely followed up in the outpatient department once every 3 months in the first two years, once every 3 to 6 months in the third year, once every 6 months starting from the fourth year, and so on. Each time, patients should be asked whether they have abdominal discomfort and digestive tract symptoms. Each time, a thorough physical examination, blood routine test, liver and kidney function test, and tumor marker test should be conducted. CT scans, ultrasounds and other imaging examinations should be conducted every six months to detect tumor recurrence and metastasis. The primary outcomes were the 5-year and 10-year overall survival rates and recurrence-free survival rates. The follow-up period is until February 1, 2025.

Overall survival (OS) is defined as the time from the end of surgery to death from any cause. Recurrence-free survival (RFS) is defined as the time from the end of surgery to tumor recurrence. Recurrence is defined as the recurrence of radiological and pathological diseases in patients who have received radical treatment. Postoperative complications were evaluated according to the Clavien-Dindo surgical complication classification system [21]. The pathological staging criteria were based on the eighth edition of AJCC [22]. Tumors located at the appendiceal root are defined as those whose base is ≤ 1 cm from the appendiceal-cecal junction, with intraoperative assessment by the surgeon and postoperative pathological confirmation of the distance. Simple appendectomy was defined as the performance of only a standard appendectomy, without additional resection of the tissues surrounding the appendiceal root or adjacent organs. Extended surgical resection was defined as any procedure that exceeded the scope of a simple appendectomy (including partial cecectomy, ileocecal resection, right hemicolectomy, etc.).

The statistical software SPSS26.0 was used for analysis. The measurement data of normal distribution were expressed as x ± s, and the differences were compared using the t-test or analysis of variance. The measurement data of skewed distribution were expressed as M (Q1, Q3), and the differences between groups were compared using the Mann-Whitney U test. Counting data were expressed as values and percentages, and the differences between groups were compared using Pearson’s chi-squared test or Fisher’s precision probability test. A bilateral P value < 0.05 was considered statistically significant. The survival curve was plotted using the Kaplan-Meier method, and survival analysis was performed using the Log-Rank test. Univariate and multivariate Cox proportional hazards regression models were used to evaluate patient characteristics and RFS.

Result

From January 1, 2013 to January 1, 2025, 58 patients were excluded according to the exclusion criteria (having other types of malignant tumors in the past 5 years, n = 22;) Tumors in other parts were combined upon admission for treatment, with n = 14; Lost to follow-up, survival date unknown, n = 9; Other malignant tumors were found during the follow-up period, with n = 8; No radical surgery or tumor biopsy was performed, n = 4; The postoperative survival time was less than 1 month, and n = 1. At the end of the study, a total of 97 patients were enrolled (the flowchart is shown in Fig. 1). Table 1 presents the clinicopathological data of the patients. The average age of the patients at the initial diagnosis was 55.87 years old, including 31 males (32.0%) and 66 females (68.0%). The median duration of symptoms was 2 months (range, 1–48 months). Most patients experienced abdominal pain (43.3%), and 12.4% of patients were found to have palpable masses at the time of visit. Among the 97 patients, six patients (6.2%) underwent emergency surgery, while ninety-one patients (93.8%) underwent elective surgery. Before the operation, 29 patients (29.90%) had elevated tumor markers, among which the patients with elevated CEA were the most (18.56%) (for details, see Table 1). Among the 97 patients, 72 cases (74.2%) underwent laparoscopic surgery. Intraoperative exploration and postoperative pathology showed perforation in 7 cases (7.2%) of patients. The postoperative pathological results of the resection margin showed that 4 cases (4.1%) had positive resection margins and 93 cases (95.9%) had negative resection margins (for detailed results, see Supplementary Table 1).

Fig. 1.

Study flow chat. LAMN= Low-grade Appendiceal Mucinous Neoplasms

Table 1.

Patient characteristics

Surgery procedure	Simple appendectomy N = 54	Extended surgical resection N = 43	P values
Age(years)	54.14 ± 15.74	57.24 ± 14.69	0.486
Sex, n (%)			0.445
Male	19(35.2%)	12(27.9%)
Female	35(64.8%)	31(72.1%)
BMI	24.29 ± 3.27	24.54 ± 3.06	0.643
Symptoms			0.781
Abdominal pain	25(46.3%)	17(39.5%)
Examination revealed	17(31.5%)	16(37.2%)
Other symptoms	12(22.2%)	10(23.3%)
Physical examination			0.539
No positive signs	22(40.7%)	23(53.5%)
Abdominal tenderness	14(25.9%)	11(25.6%)
Abdominal mass	8(14.8%)	4(9.3%)
Others	10(18.5%)	5(11.6%)
Underlying disease			0.826
Yes	34(63.0%)	28(65.1%)
No	20(37.0%)	15(34.9%)
Operation history			0.351
Yes	16(29.6%)	13(30.2%)
No	38(70.4%)	30(69.8%)
Smoking history			0.483
Yes	9(16.7%)	5(11.6%)
No	45(83.3%)	38(88.4%)
Alcohol history			0.592
Yes	9(16.7%)	9(20.9%)
No	45(83.3%)	34(79.1%)
High tumor markers			0.129
Yes	18(33.30%)	8(18.6%)
No	36(66.7%)	35(81.4%)
CEA			0.143
High	13(24.1%)	6(14.0%)
Normal	41(75.9%)	37(86.0%)
CA12-5			0.730
High	5(9.3%)	3(7.0%)
Nomal	49(90.7%)	40(93.0%)
CA72-4			0.458
High	5(9.3%)	2(4.7%)
Nomal	49(90.7%)	41(95.3%)
Surgery			0.453
Elective Surgery	50(92.6%)	41(95.3%)
Emergency Surgery	4(7.4%)	2(4.7%)

Results expressed as mean ± standard deviation (SD) or Q2 (Q1, Q3) or as n (%)

BMI Body mass Index, ASA American society of anesthesiologists, PCI Peritoneal cancer index, PMP Pseudomyxoma peritonei, CEA Carcinoembryonic antigen, CA Cancer antigen

The time of the first postoperative anal exhaust in the two groups of patients was 1 (1, 2) days and 2 (2, 3) days respectively. A comparison between the two showed a statistically significant difference (P < 0.001). The hospitalization times were 5 (4,6) days and 11 (8,17) days respectively. A comparison between the two showed a statistically significant difference (P < 0.001). Postoperative electrolyte imbalance (11 out of 54 cases [20.4%] vs. 23 out of 43 cases [53.5%]; P = 0.001), incidence of serum hypoalbumin (31 out of 54 cases [57.4%] vs. 38 out of 43 cases [88.4%]; P = 0.001), elevated blood glucose (12 out of 54 cases [22.2%] vs. 23 out of 43 cases [53.5%]; P = 0.001) The incidence rate in the simple appendectomy group was significantly higher than that in the extended surgical resection group (for detailed results, see Table 2). Among the 97 patients, 18 cases had postoperative complications, with 6 cases and 12 cases in the two groups respectively. A comparison between the two showed a statistically significant difference (P = 0.040). The number of patients with Clavien-DinDOis-grade II, grade IIIa, grade IIIb and grade IVa complications was 13, 4, 4 and 1 respectively. Among the patients with grade I-II complications, there were 4 cases of respiratory system complications, 3 cases of incision infection and poor healing, 2 cases of urinary retention, 1 case of anastomotic fistula and intestinal fistula, 1 case of abdominal cavity infection, 1 case of intestinal obstruction, and 1 case of thrombosis. Among the patients with grade IIIa complications, there was 1 case each of respiratory system complications, gastrointestinal bleeding, abdominal cavity infection and intestinal obstruction. Among the patients with grade IIIb complications, there were 2 cases of gastrointestinal bleeding, 1 case of intestinal obstruction and 1 case of pulmonary embolism. Patients with grade IVa complications were those with anastomotic fistula complications. The same patient can have multiple complications. (For detailed results, please refer to Table 2). Intraoperative examination revealed that none of the 97 patients exhibited grossly evident intraperitoneal mucus.

Table 2.

Short-term outcomes

Surgery procedure	Simple appendectomy N = 54	Extended surgical resection N = 43	P values
First exhaust time(days)	1(1, 2)	2(2, 3)	<0.001
First defecation time(days)	3(2, 3)	4(3, 5)	<0.001
First time out of bed activity(days)	1(1, 2)	2(1, 2)	<0.001
Complications, n (%)			0.040
Yes	6(11.1%)	12(27.9%)
No	48(88.9%)	31(72.1%)
Clavien-Dindo classification, n (%)			0.767
I-II	5(9.3%)	8(18.6%)
III a	1(1.9%)	3(7.0%)
III b	2(3.7%)	2(4.7%)
IV a	0	1(2.3%)
Electrolyte disturbance, n (%)			0.001
Yes	11(20.4%)	23(53.5%)
No	43(79.6%)	20(46.5%)
Lower hemogolobin, n (%)			0.022
Yes	20(37.0%)	26(60.5%)
No	34(63.0%)	17(39.5%)
Albumin deficiency, n (%)			0.001
Yes	31(57.4%)	38(88.4%)
No	23(42.6%)	5(11.6%)
High leukocyte count, n (%)			0.117
Yes	24(44.4%)	26(60.5%)
No	30(55.6%)	17(39.5%)
Elevated blood glucose, n (%)			0.001
Yes	12(22.2%)	23(53.5%)
No	42(77.8%)	20(46.5%)
Hospital stays(days)			<0.001
Median(Q1,Q3)	5(4, 6)	11(8, 17)
Expense(dollar)			<0.001
Median(Q1,Q3)	3001.8(2504.1, 4317.6)	6952.4(3075.8, 8391.3)

Data are presented as n (%) or Q2 (Q1, Q3) unless otherwise indicated

As of the last follow-up, among the 97 patients, 11 cases (11.3%) died, 10 cases were due to tumors and 1 case was due to other reasons. Thirteen cases (13.4%) relapsed, and the most common recurrence sites were the omentum and paracolonic sulcus. Among the 13 relapsed patients, 3 survived after treatment, including 1 case of surgery and 2 cases of surgery combined with chemotherapy. The median follow-up time was 56 months (range, 16–117 months). The Kaplan-Meier method predicted that the 5-year and 10-year overall survival rates of 54 patients in the simple appendectomy group were 88.9% and 85.2%, respectively, while the predicted survival rates of 43 patients in the other surgical method group were 95.3% and 93.0%. There was no significant difference in the results between the two groups (χ²=1.371, P = 0.242; χ²=1.905, P = 0.167) (Supplemental Fig. 1). Similarly, the 5-year and 10-year recurrence-free survival rates in the simple appendectomy group were 87.0% and 83.3%, respectively, while those in the other surgery group were 93.0% and 90.7%, respectively. There was no significant difference in the results between the two groups (χ²=1.089, P = 0.297; χ²=1.548, P = 0.213) (Supplemental Fig. 2).

Among the 97 patients, 6 were found to have intraoperative tumor perforation upon exploration or postoperative pathological examination, and 4 had positive surgical margins. To eliminate the potential impact of tumor perforation and positive margins on assessing the safety and efficacy of simple appendectomy for low-grade appendiceal mucinous neoplasms at the appendiceal root, these 10 patients were excluded from the survival analysis of the two groups. The Kaplan-Meier method predicted 5‑year and 10‑year overall survival rates of 95.7% vs. 97.5% and 90.5% vs. 95.7%, respectively, with no significant difference between the two groups (χ²=0.173, P = 0.677; χ²=0.006, P = 0.937) (Fig. 2). Similarly, the Kaplan-Meier method predicted 5‑year and 10‑year recurrence-free rates of 95.0% vs. 93.6% and 92.5% vs. 91.5%, respectively, also showing no significant difference between the groups (χ²=0.068, P = 0.795; χ²=0.094, P = 0.759)(Fig. 3). Therefore, for patients with low-grade appendiceal mucinous neoplasms at the appendiceal root who have negative margins and no tumor perforation, simple appendectomy represents a safe and viable surgical option.

Fig. 2.

Kaplan-Meier survival estimates for patients with low-grade appendiceal mucinous neoplasm at the appendiceal root with negative margins. A 5-years overall survival for patients following simple appendectomy and the extended surgical resection group (X²=0.173; P=0.677). B 10-years overall survival for patients following simple appendectomy and Extended surgical resection group (X²=0.006, P= 0.937)

Fig. 3.

Kaplan-Meier survival estimates for patients with low-grade appendiceal mucinous neoplasm at the appendiceal root with negative margins (A) 5-years recurrence-free survival for patients following simple appendectomy and control group (X²=0.068; P=0.795). B 10-years recurrence-free survival for patients following simple appendectomy and Extended surgical resection group (X²=0.094, P=0.759)

Tables 3 and 4 respectively summarize the univariate and multivariate Cox proportional hazards models of OS and RFS. Age [Hazard ratio (HR) = 1.057; P = 0.041], elevated serum CEA[HR = 7.967; P = 0.002], elevated CA12−5 [HR = 15.314; P = 0.001], elevated CA72−4 [HR = 5.246; P = 0.015], positive resection margin [HR = 8.201; P = 0.002], tumor perforation [HR = 4.673; P = 0.023], tumor size [HR = 2.866; P = 0.008] and tumor stage T4a [HR = 7.045; P = 0.047] were significantly correlated with OS. All these predictive factors were included in the multivariate analysis. Tumor size [HR = 2.822; P = 0.008] and tumor stage T4a [HR = 7.045; P = 0.047] were the predictive factors retained in the final OS model. Advanced age [HR = 1.063; P = 0.019], elevated preoperative serum CEA [HR = 8.867; P = 0.001], elevated CA12−5 [HR = 10.376; P = 0.001], elevated CA72−4 [HR = 4.871; P = 0.016], positive resection margin [HR = 8.436; P = 0.001], tumor perforation [HR = 4.470; P = 0.023], large tumor volume [HR = 2.896; P0.001] and late tumor T stage [HR = 5.476; P = 0.003] have a higher risk of disease recurrence. Large tumor volume [HR = 2.218; P = 0.001] and late tumor T stage [HR = 7.715; P = 0.015] were the predictive factors retained in the final RFS model; The increase of serum CA12−5 [HR = 8.852; P = 0.065] was not statistically significant, but it did show a significant trend.

Table 3.

Univariate and multivariate analysis of OS in 97 patients with LAMN

Characteristic	Variable	Univariate analysis			Multivariate analysis
		HR	95% CI	P	HR	95% CI	P
Age		1.057	1.002, 1.114	0.041	1.013	0.950, 1.080	0.690
Sex	Male versus Female	1.241	0.362, 4.249	0.731
Smoking history	Yes versus No	1.604	0.346, 7.441	0.546
Alcohol history	Yes versus No	1.600	0.423, 6.054	0.489
Underlying disease	Yes versus No	1.519	0.402, 5.738	0.537
CEA	Abnormal versus Normal	7.967	2.199, 28.869	0.002	1.964	0.304, 8.930	0.774
CA12-5	Abnormal versus Normal	15.314	4.286, 54.730	<0.001	7.281	0.762, 69.558	0.085
CA72-4	Abnormal versus Normal	5.246	1.384, 19.883	0.015	2.248	0.200, 25.298	0.512
Amount of bleeding		1.998	0.990, 2.006	0.637
Type of Procedure	Laparoscopy versus Laparotomy	0.656	0.191, 2.253	0.503
Tumor size		2.896	1.802, 4.655	<0.001	2.822	1.307, 6.096	0.008
Margin status	Positive versus Negative	8.201	2.167, 31.034	0.002	2.495	0.186, 33.459	0.490
Tumor perforation	Yes versus No	4.673	1.236, 17.673	0.023	1.558	0.157, 16.034	0.695
Tumor T stage	T4a versus Others	4.873	1.421, 16.707	0.012	7.045	1.025, 48.426	0.047
Lymph node dissection	Yes versus No	1.150	0.305, 4.339	0.837
Complications	Yes versus No	1.105	0.239, 5.119	0.898
Clavicle-Dindo ≥ III	Yes versus No	0.993	0.127, 7.751	0.993

OS Overall survival, HR Hazard ratio, CI Confidence interval, CEA Carcinoembryonic antigen, CA cancer antigen

Table 4.

Univariate and multivariate analysis of RFS in 97 patients with LAMN

Characteristic	Variable	Univariate analysis			Multivariate analysis
		HR	95% CI	P	HR	95% CI	P
Age		1.063	1.010, 1.119	0.019	1.032	0.973, 1.095	0.295
Sex	Male versus female	0.975	0.300, 3.170	0.967
Smoking history	Yes versus No	1.993	0.547, 7.255	0.269
Alcohol history	Yes versus No	2.148	0.590, 7.828	0.246
Underlying disease	Yes versus No	2.053	0.632, 6.671	0.232
CEA	Abnormal versus normal	8.867	2.557, 30.752	0.001	2.082	0.336, 12.893	0.431
CA12-5	Abnormal versus normal	10.376	2.667, 40.379	0.001	1.707	0.145, 20.068	0.671
CA72-4	Abnormal versus normal	4.871	1.336, 17.758	0.016	8.852	0.875, 89.509	0.065
Amount of bleeding		0.997	0.988, 1.006	0.490
Type of Procedure	Laparoscopy versus Laparotomy	0.436	0.146, 1.305	0.138
Tumor size		2.722	1.785, 4.150	<0.001	2.218	1.379, 3.567	0.001
Margin status	Positive versus negative	8.436	2.303, 30.898	0.001	4.694	0.560, 39.337	0.154
Tumor perforation	Yes versus No	4.470	1.227, 16.292	0.023	2.239	0.331, 15.129	0.408
Tumor T stage	T4a versus others	5.476	1.780, 16.848	0.003	7.715	1.492, 39.894	0.015
Lymph node dissection	Yes versus No	0.920	0.257, 3.405	0.920
Complications	Yes versus No	1.251	0.342, 4.569	0.735
Clavicle-Dindo ≥ III	Yes versus No	0.862	0.112, 6.656	0.887

RFS Relapse-free survival, HR Hazard ratio, CI Confidence interval, CEA Carcinoembryonic antigen, CA Cancer antigen

Discussion

Through the above research, we draw the conclusion that for LAMN at the root of the appendix without metastasis, simple appendectomy is a safe and effective radical treatment method. We found that patients with root LAMN who underwent simple appendectomy did not have a reduced survival expectation. Patients with T4a in tumor stage T and large tumor volume have an increased risk of death and tumor recurrence. Therefore, closer follow-up monitoring and intervention are needed for these patients.

Surgical treatment is currently recognized as the preferred treatment method for LAMN, and other adjuvant treatments after surgery are also feasible [9]. De Moortele et al. [10] argued that patients with Tis (LAMN) can usually be treated with appendectomy without the risk of recurrence. In view of the uncertainty of peritoneal transmission risk in patients with T3 LAMN, close follow-up should be considered to evaluate the development of peritoneal diseases. However, the time, frequency and role of imaging examinations during the follow-up process have not been determined yet. For patients with LAMN T4a and those without giant cell proteins on the visceral peritoneal surface, similar to those with LAMN T3, close follow-up is recommended. For LAMN T4a patients with cellular mucin deposition on the visceral peritoneal surface, due to their relatively high peritoneal recurrence rate, some centers recommend HIPEC treatment [18].

Due to the rarity of appendiceal tumors, conducting prospective controlled studies is difficult and involves ethical issues. Due to the rarity of appendiceal tumors, conducting prospective controlled studies is difficult and involves ethical issues. At present, there are no large-sample and high-quality prospective studies on the optimal surgical method for LAMN. Therefore, retrospective research remains an indispensable research method. Gonzalez-Moreno et al. [11] reviewed 501 patients diagnosed with epithelial appendiceal tumors and found that right hemicolectomy had no survival advantage compared with appendectomy alone. Bassel F-El-Rayes et al. [9] hold that appendectomy alone is sufficient to treat tumors that only present local lesions. If a tumor is involved after appendectomy, a right small colectomy should be considered to remove the tumor margin. However, these studies all have different limitations: they are limited to the elderly and alone, without LAMN analysis and appendiceal tumors, some definitions have changed, or the sample size is small and biased. Therefore, there is an urgent need for large-sample, high-quality, and more retrospective cardiac cohort studies to optimize our understanding of low appendiceal mucin levels and tumor treatment.

Compared with other gastrointestinal malignancies, our research results show that the prognosis of patients with LAMN is generally better, which is related to its low malignancy and slow development of LAMN. Therefore, the prognosis of the patient is not related to the scope of the surgery. Since residual tumors are regarded as one of the risk factors associated with poor prognosis, it is recommended to ensure the safety of the surgical margin and achieve complete elimination of the tumor through reasonable surgical resection. In this case, a simple appendectomy can achieve a satisfactory long-term prognosis without any extensive surgery. In addition, compared with appendectomy and ileocectomy, right hemicolectomy has significant adverse effects on short-term prognosis such as surgical complications, nutritional status, blood glucose control, water and electrolyte balance, length of hospital stay and cost.

Since we excluded patients with tumor metastasis, PMP was not included in this study. PMP is the formation of multiple mucus nodules on the peritoneal surface due to the restricted or extensive accumulation of mucus within the tumor epithelium of the peritoneum [23]; Most peritoneal mucinous pseudotumors are the result of the progression of appendiceal mucinous tumors. Sometimes mucinous carcinomas in other parts can also lead to peritoneal mucinous pseudotumors. PMP affects approximately one in a million people each year and causes approximately 40% of patient deaths annually [24]. It is generally believed that the best treatment plan is CRS + HIPEC [19, 20].

This study included 97 patients with LAMN, among whom 11 died and 13 relapsed during the follow-up period, showing a low recurrence rate and tumor-related mortality rate. A total of 97 LAMN patients were included in this study, among whom 11 died and 13 experienced recurrence during the follow-up period. Additionally, the study included 6 patients with tumor perforation and 4 patients with positive surgical margins. After excluding these patients, analysis of the remaining 87 cases revealed only 4 deaths and 7 recurrences. Kaplan-Meier survival analysis was performed again, and the results indicated that simple appendectomy did not compromise the survival prognosis of patients with low-grade appendiceal mucinous neoplasms at the appendiceal root. Therefore, provided that an R0 resection is achieved, simple appendectomy is a safe surgical approach. Moreover, compared to extended resection, simple appendectomy offers advantages such as reduced trauma, faster recovery, and lower surgical costs. For patients with tumor perforation, our previous research has shown that CRS + HIPEC treatment significantly reduces mortality and recurrence compared to CRS alone [25]. Among the 4 patients with positive margins in this study, 3 died. Therefore, for patients with positive margins, we recommend undergoing reoperation to achieve negative margins, thereby reducing mortality risk.

This study still has limitations: (1) This study is a retrospective study. This inherent limitation may have led to selection bias. Therefore, prospective studies are needed to verify the results of this study. (2) The follow-up time was relatively short, with a median follow-up time of 56 months. Therefore, it cannot be ruled out that the survival outcomes of LAMN patients who receive different surgical methods after long-term follow-up will be different. (3) Potential confounding factors: Despite multivariate analysis, there may still be unidentified or uncontrolled confounding factors. In addition, for some prognostic factors, mainly through telephone or outpatient follow-up, there may be some subjective confounding factors influencing them. (4) Surgical techniques and postoperative management may vary among different hospitals, which may affect the interpretation of the results. This is an inherent defect of various heart studies.

Conclusion

In conclusion, we retrospectively analyzed the clinical data of 97 patients with LAMN. For patients with LAMN at the root of the appendix, simple appendectomy is a safe and effective surgical method. Therefore, for patients with root LAMN, a simple local appendectomy with a negative resection margin is sufficient. In addition, simple appendectomy causes less trauma to patients and has advantages in reducing surgical complications, shortening the operation time and shortening the hospital stay. Tumor stage T4a and larger tumor volume are associated with an increased risk of death and tumor recurrence in patients with LAMN. Finally, the research of this paper provides a basis for the subsequent research.

Authors’ contributions

Z.H. ，Y.Z. , and J.S. made significant contributions to the conception and design of the study. W.T. and Y.G. were responsible for data acquisition. S.G. and H.Z. performed data analysis and interpretation. Z.H. and Y.Zh. drafted the initial manuscript, while C.X. conducted substantive revisions. All authors (Z.H., W.T., C.X., Y.G., S.G., H.Z., Y.Zh., Y.Z., J.S.) reviewed and approved the final version of the manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability

The datasets generated and/or analyzed during the current study are not publicly available due to patient privacy and ethical restrictions. However, they are available from the corresponding author upon reasonable request. The data were provided by Beijing Hospital and the Affiliated Hospital of Qingdao University under specific agreements for this study. Any further use or sharing of the data must obtain permission from the original data providers (i.e., the aforementioned hospitals) and comply strictly with their respective data management policies and ethical review requirements.

Declarations

Ethics approval and consent to participate

The research procedure was approved by the Institutional Review Board and was conducted in accordance with the ethical standards of the Declaration of Helsinki in 1975.

Competing interests

The authors declare no competing interests.