Gender and age

During the period January 2004 to January 2023 11,888 appendicectomies were performed due to suspicion of AA at South General Hospital in Stockholm; 46% were females and 54% males. From the combined AA and colon cancer registers, 148 patients with an appendix tumour were found, 89 females (60%) and 59 males (40%), all except two (with widespread disease) were resected. Of these patients 107 came from the AA register and 97 from the KVALOG, i.e. some were recorded in both registers. Age groups for patients with AA, appendix tumor and rate of tumours compared to AA are presented in Table 1.

Table 1 Numbers of operations for AA and appendiceal tumours in age-groups

For the group with a tumour the median age were 56 years (Q1 = 43, Q3 = 70) (78.4% were 41 years or older), while the corresponding figure for the patients with AA were median age 32 (Q1 = 21, Q3 = 47) (33.7% 41 years or older) (Table 1).

The use of preoperative imaging, abdominal ultrasound (US) or computer tomography (CT), was 30% in 2004 increasing to 93% in 2014 [14]. In 2022, 99% of patients had a preoperative radiology.

Mortality and survival in tumour patients

Among the 11,888 patients in the AA register 14 (0.12%) patients died within 30 days after the operation. These were elderly patients with multiple comorbidities. By the end of the follow-up, 35 tumour patients had died, 19 women and 16 men.

The overall 5-year survival in patients operated for LAMN was 96.8%, for NET 93.3% and for adenocarcinoma 69.7% (Fig. 1). The overall 5-year survival for all tumour patients was 85.7%.

Fig. 1

Survival of all tumour patients in the NET-, LAMN- and adenocarcinoma groups

In the tumour group 76% were still alive at the final day of follow-up. One-year survival was 89.2%, 5.4% died and 5.5% were not followed-up one year after the operation. Five-year survival was 51.4%, 13.7% died and 34.9% still alive were not followed up 5 years after the operation.

Most of patients survived one year, but many had not been followed up at 5 years postoperatively by the last follow-up date. The majority of those who died were sick and elderly.

Patients who received adjuvant treatment had a poorer 5-year survival; 56% compared to 90% alive without adjuvant treatment.

In general, groups differed regarding survival time (NET, LAMN and Carcinoma), where the Carcinoma-group had the lowest survival time (p < 0.001) (Fig. 1). Females in the cancer group had lower survival compared to those in the LAMN- and NET-groups (p < 0.001) (Fig. 2). For males there were no difference between the tumour groups (p = 0.22) (Fig. 3).

Fig. 2

Survival of females in the NET-, LAMN- and adenocarcinoma groups

Fig. 3

Survival of males in the NET-, LAMN- and adenocarcinoma groups

Patients younger than 50 years at surgery had similar survival rates in the three groups (p = 0.12), but the number of patients was small (Fig. 4). No differences in survival were seen between the tumour groups among patients older than 50 years at the time of operation (Fig. 5).

Fig. 4

Survival of patients older than 50 years in the NET-, LAMN- and adenocarcinoma groups

Fig. 5

Survival of patients 50 years or younger in the NET-, LAMN- and adenocarcinoma groups

Surgery for appendix tumours

At surgery, 26.2% of the AA patients had a perforation. The perforation rate did not change significantly over the period of the study. Tumour patients had approximately the same perforation rate (25.3%) as patients with benign acute appendicitis.

The surgeon suspected a tumour intraoperatively in 62% of the tumor patients, whereas in 38% the tumour was discovered incidentally at histopathology examination. Of those who were diagnosed with appendiceal tumours, suspicion was already raised at preoperative radiology in 41% of cases.

In the AA quality register during the study period, 62.5% underwent laparoscopic appendicectomy, 33% appendicectomy through an open transverse incision, 1.9% through an open midline incision and 0.1% through an open paramedian incision. In 2004, 6% were laparoscopic appendicectomies and in 2022 the figure was 99%.

In the group of tumour patients undergoing surgery (n = 146) primary surgery was laparoscopic in 47% and open in 52%. Two patients did not undergo surgery due to widespread disease. In 64% of cases operation was acute, whereas it was delayed and/or planned in 34%. Most procedures were laparoscopic appendicectomy 36%, followed by open appendicectomy 30%, right-sided hemicolectomy 14.6% (open 11.6% and laparoscopic 3%, acute operation 5.5%), ileocecal resection 5% (acute operation 3.4%) and staging laparoscopy 7%. Two patients had CRS and HIPEC as the initial operation.

Forty-three per cent of the 146 tumour patients operated underwent a second procedure. CRS and HIPEC in 23.3%, and right-sided hemicolectomy in 13.6% (laparoscopic 8.2%, open 5.4%).

At primary surgery, the surgeon did not suspect a tumour in 38% of the cases, but a tumour was later found at histopathology. In the remaining there was at least a minor suspicion of tumour (62%). When the primary surgery was performed, a radical resection of the tumor was seen in 65% of the 146 operated tumour patients. Of 148 patients, 107 (72.3%) were followed up in the policlinic and 41 (27.7%) were not.

Postoperative complications in tumor patients

93% of the tumour patients had no surgical complication after the primary procedure. Two had intraabdominal abscesses, 8 paralytic ileus and 4 surgical site infection. Ten patients suffered various medical complications.

Tumour patients and PAD

In 2004, only 36.6% of the appendicectomies carried out for benign AA had a specimen sent for histopathology examination (PAD), while in 2022 the rate was 96.3%. All tumours in the present study were confirmed at histopathology.

Among the 148 patients with an appendix tumours; 64 had LAMN, 57 carcinomas of some form, 24 NET and 3 an adenoma. Of those with LAMN, 15 had pseudomyxoma peritonei at the time of diagnosis. The carcinoma group included: adenocarcinoma, signet ring adenocarcinoma, goblet cell carcinoma and mucinous adenocarcinoma. In this group 8 had peritoneal carcinosis at diagnosis. Two did not undergo appendicectomy since the tumour was found to be disseminated at diagnosis (radiology and biopsy).

Follow-up, oncology treatment, recurrence

Of the tumour patients 28% went without follow-up, whereas 72% were followed at least with at least outpatient visits. The majority of those who were followed up did not undergo adjuvant treatment (64%), whereas 34% received adjuvant therapy of some kind. At the final day of follow-up May 15th, 2023, 79% of the tumour patients were without recurrence, 10% had disseminated cancer already at diagnosis, and 11,5% developed recurrent disease.

Hospital stays after the primary operation

53% of the tumour patients stayed 1–3 days after the first or only operation, 26% 4–6 days and 21% more than 6 days.

Causes of death in tumor patients

More than half(18) of 35 patients who died had disseminated cancer as cause of death, especially appendix/colorectal cancer (51.4%), the remainder died of causes not related to the appendix cancer. Of those who died, 32 were 51 years or older at the operation. Cardiac infarction, stroke, pneumonia and hepatic failure were the first obvious causes of death in several cases, while the cause of death was unknown in 3 cases.