We included 383 patients, and their characteristics are summarized in Table 1. The median age was 61 years (26-86 years). Most patients had pT1 disease (65.5%).
Table 1: Clinical characteristics of the 383 patients
Characteristic
|
Patients (N = 383)
|
Age at CT scan, years, median (range)
|
61 (26-86)
|
Sex (female)
|
382 (99)
|
Tumor size
|
|
pT1 (£20 mm)
|
251 (66)
|
pT2 (20-50 mm)
|
98 (26)
|
pT3 (>50 mm)
|
11 (3)
|
pT4 (Any size /direct extensiona)
|
2 (0.5)
|
Unknown primary tumor
|
4 (1)
|
Carcinoma in situ (ductal or lobular)
|
17 (4)
|
Lymph nodes
|
|
pN0 (No regional lymph node metastasis)
|
206 (54)
|
pN1 (1-3 axillary lymph nodes)
|
125 (33)
|
pN2 (4-9 axillary lymph nodes)
|
22 (6)
|
pN3 (³10 axillary lymph nodes or b)
|
13 (3)
|
Carcinoma in situ (ductal or lobular)
|
17 (4)
|
Histopathological classification
|
|
Carcinoma in situ (ductal or lobular)
|
17 (4)
|
Invasive ductal carcinoma
Invasive lobular carcinoma
|
287 (75)
44 (12)
|
Mixed invasive lobular and ductal carcinoma
|
10 (3)
|
Other malignant tumorsc
|
25 (7)
|
Type of surgery
|
|
Lumpectomy
|
309 (81)
|
Mastectomy
|
70 (18)
|
No surgeryd
|
4 (1)
|
Sentinel node (SN)
|
237 (62)
|
Axillary lymph node dissection
|
133 (35)
|
Neither SN nor node dissection
|
13 (3)
|
Data are presented as n (%) unless otherwise indicated.
aExtension to the chest wall or skin.
bAxillary, infraclavicular, or ipsilateral supraclavicular lymph nodes.
cMucinous adenocarcinoma (n = 11), metaplastic carcinoma (n = 2), apocrin carcinoma (n = 1), invasive solid papillary carcinoma (n = 5), tubular carcinoma (n = 2), adenocarcinoma (n = 2), secretory carcinoma (n = 1), and intracystic carcinoma (n = 1).
dDue to unknown primary tumor.
Organ distribution of incidental findings
A total of 513 IFs were detected: 433 by the radiologists and 80 by the oncologists. The radiologist and oncologists detected an average of 1.1 and 0.2 IFs per patient, respectively. The radiologists detected potential malignant lesions in 94 patients (25%), whereas the oncologists found potential malignant lesions in only 34 patients (9%). By contrast, the radiologists detected benign IFs in 162 (42%) patients, whereas the oncologists noted benign IFs in 39 patients (10%).
The breast, liver, and lungs were the most frequent locations of IFs. The distribution of IFs by organ is shown in Table 2. If a patient presented with several IFs, each IF was registered according to its anatomic location, independent of the individual patient. The breast was the most common site of benign findings registered by the radiologists (83 IFs), whereas the liver was the most common site of benign findings detected by the oncologists (16 IFs). The liver was the most frequent site of potential malignant lesions; the radiologists reported 41 IFs in the liver, whereas the oncologists noted 19. The majority of potential malignant lesions were located in the liver and lungs.
Table 2: Distribution of incidental findings registered by the radiologists and oncologists
|
Radiologists
|
Oncologists
|
Distribution of incidental findings by organa
|
Potential malignant IF
|
Benign IF
|
Potential malignant IF
|
Benign
IF
|
Liver
|
41
|
56
|
19
|
16
|
Lungs
|
25
|
45
|
12
|
4
|
Lymph nodes
|
13
|
4
|
2
|
2
|
Bones
|
12
|
11
|
0
|
1
|
Subcutaneous
|
4
|
1
|
0
|
0
|
Axilla
|
3
|
22
|
0
|
1
|
Kidneys
|
3
|
14
|
1
|
1
|
Breast
|
2
|
83
|
1
|
9
|
Adrenal glands
|
2
|
12
|
0
|
0
|
Thyroid gland
|
1
|
31
|
1
|
4
|
Thoracic wall
|
1
|
0
|
0
|
0
|
Gall bladder
|
0
|
20
|
0
|
1
|
Stomach and esophagus
|
0
|
12
|
0
|
2
|
Pleura
|
0
|
5
|
0
|
0
|
Pancreas
|
0
|
3
|
0
|
0
|
Vessels
|
0
|
2
|
0
|
0
|
Mediastinum
|
0
|
1
|
0
|
1
|
Heart
|
0
|
1
|
0
|
0
|
Colon
|
0
|
1
|
0
|
0
|
Mesentery
|
0
|
1
|
0
|
0
|
Paravertebral
|
0
|
1
|
0
|
0
|
Muscles
|
0
|
0
|
1
|
0
|
Total IFs
|
107
|
326
|
37
|
42
|
|
|
|
|
|
|
aSome patients had more than one incidental finding on the computed tomography scan.
IF: incidental finding
Interobserver variability
The associations between the potential malignant lesions detected by radiologists and oncologists are shown in Table 3. Of the 383 included patients, the radiologists registered 97 patients with IFs in the liver and 70 with IFs in the lungs. By contrast, the oncologists reported 35 patients with IFs in the liver and 16 with IFs in the lungs.
Table 3: Two by two tables summarizing the number of patients with and without incidental findings in the A) liver and B) lungs registered by the oncologists and the radiologists
- Liver
|
|
Radiologists
|
|
Incidental findings (all types)
|
Yes (%)
|
No (%)
|
Total (%)
|
|
Yes (%)
|
28 (7)
|
7 (2)
|
35 (9)
|
Oncologists
|
No (%)
|
69 (18)
|
279 (73)
|
348 (91)
|
|
Total (%)
|
97 (25)
|
286 (75)
|
383 (100)
|
|
|
|
|
|
- Lungs
|
|
Radiologists
|
|
Incidental findings (all types)
|
Yes (%)
|
No (%)
|
Total (%)
|
|
Yes (%)
|
14 (3.7)
|
2 (0.5)
|
16 (4.2)
|
Oncologists
|
No (%)
|
56 (15)
|
311 (81)
|
367 (96)
|
|
Total (%)
|
70 (18)
|
313 (82)
|
383 (100)
|
If a patient had an IF in both the liver and lungs, they were included in both tables. The numbers in brackets represent the percentage of the total number of patients. IF: incidental finding
Interobserver agreement
For IFs in the liver, the observed accuracy was 80%, and the expected agreement was 70%. The kappa value for IFs in the liver was 0.33. The observed agreement for IFs in the lungs was 85%, and the expected agreement was 79%. For IFs in the lungs, the kappa was 0.28.
Sensitivities, specificities, and predictive values of incidental findings
The oncologists’ sensitivities for detecting IFs in the liver and lungs were 29% and 20%, respectively. The specificities in the liver and lungs were 98% and 99%, respectively. Regarding the predictive values, the PPVs were 80.0% in the liver and 88% in the lungs, and the corresponding NPVs were 80% and 85%, respectively. The false positive rate was 20% for the liver and 12,5 % for lungs.