Background
Approximately 5–10% of the breast cancers follows an autosomal dominant inheritance pattern and is characterized as hereditary. The high-risk breast cancer susceptibility genes
BRCA1 and
BRCA2 account for up to 30% of these hereditary cases, which leaves a large proportion of familial clustering unexplained [
1]. Other breast cancer predisposing genes have been identified including
ATM, CHEK2, PALB2, PTEN, TP53 and
CDH1 [
2‐
6].
The founder germline pathogenic variant
CHEK2 c.1100del (hereafter referred to as
CHEK2 PV) is present in approximately 0.2 to 1.6% of individuals of Northern and Eastern European descent [
4,
7,
8]. In the Netherlands, this PV is present in 1.1% of the general population and in approximately 5% of breast cancer cases with a family history of breast cancer [
3]. It has been shown that
CHEK2 heterozygotes with a family history of breast cancer have a two- to threefold increased risk of breast cancer [
3,
9‐
11], classifying it as a moderate risk variant. In addition, the risk of contralateral breast cancer is more than two times as high in patients with the
CHEK2 PV compared to patients without this PV [
12]. Homozygosity for the
CHEK2 PV is rare, but seems to be associated with a higher breast cancer risk [
13,
14].
As of September 2014, routine genetic testing for newly referred breast cancer patients in the Netherlands includes testing for the
CHEK2 PV [
14]. Based on the current criteria, women are also eligible for additional
CHEK2 testing if they had previously undergone
BRCA1/2 testing and no PV was detected.
Based on the clinical implications for patients and family members with the CHEK2 PV and the rather high prevalence in the patient population, it was considered good clinical care to offer additional CHEK2 testing to women counseled before September 2014, with a negative BRCA1/2 test result. As we expect more cancer-predisposing genes to be discovered in the near future, our experience with active recontact may be increasingly important for patients with breast cancer who earlier tested negative for PVs in known cancer genes.
The aims of the study were (1) to assess the uptake of recontacting BRCA1/2-negative women for additional CHEK2 PV testing, and (2) to explore patients’ experiences with these approach.
Results
Of the 2377 women recontacted, 70% (
N = 1666) responded positively to our invitation to have additional testing done for the
CHEK2 PV. In total, 66 women (almost 4%) from 64 families were found to be heterozygous for this PV. No women homozygous for the PV were found. The 1600 proven non-carriers received their test result in writing. The baseline characteristics of the
CHEK2 PV carriers are described in Table
1.
Table 1
Characteristics of the CHEK2 c.1100del index PV carriers (N = 66)
Breast cancer | 64 | 44.8 | 21 | 64 |
2nd breast cancer | 18 | 52.1 | 35 | 67 |
Other cancer | 7 | 54.2 | 39 | 66 |
Ovarian cancer (borderline) | 3 (2) | 50.3 | 39 | 65 |
Skin (1 melanoma; 3 undefined) | 4 | 58 | 53 | 66 |
Receptor status | Pos (%) | Neg. (%) | Some amplifaction (%) |
Oesterogen (N = 48) | 44 (91.7%) | 4 (8.3%) | |
Progesteron (N = 47) | 37 (78.7%) | 10 (21.3%) | |
HER2neu amplification (N = 35) | 9 (25.7%) | 24 (68.6%) | 2 (5.7%) |
| Ductal | Lobular | Ductal with lobular features |
Histopathology known (N = 53) | 45 (84.9%) | 5 (9.4%) | 3 (5.7%) |
Family history | Yes (%) | No (%) | Unknown (%) |
Breast cancer | 51 (77.3%) | 14 (21.2%) | 1 (1.5%) |
1st-degree only | 23 |
2nd-degree only | 14 |
Both 1st- and 2nd-degree | 13 |
Families with other cancers in 1st degree relatives | 32 (48.5%) | 33 (50.0%) | 1 (1.5%) |
N Cancers in 1st-degree relativesa | 40 (60.6%) | | |
Almost all PV carriers had been diagnosed with breast cancer (64 out of 66), with a mean age at diagnosis of 49 years. In the breast cancer patients with the CHEK2 PV in our study, 91.7% had estrogen-receptor-positive cancer, 78.8% had progesterone-receptor-positive cancer and 68.8% had a negative epidermal growth factor receptor 2 (HER2)-status.
Although ovarian-cancer-only families were excluded from our study, three of 66 index PV carriers were diagnosed with either ovarian cancer or borderline ovarian tumor. Two of these women were also diagnosed with breast cancer.
The majority of the index PV carriers (77.3%) had first- and/or second-degree family members with breast cancer, and 60.6% had at least one first-degree family member with another malignancy besides breast cancer, such as colorectal, prostate, ovarian and endometrial cancer (see Table
1).
All 66 CHEK2 PV carriers received their test result in-person at the genetics department and were counseled about breast cancer risk, surveillance strategies and the implications for their family members. After the counseling, a family letter was provided to facilitate disclosure of the test result within the family.
To evaluate the patients’ experiences of our approach, a questionnaire was sent to all
CHEK2 PV carriers (cases) who were alive (
N = 65) and an age-matched control group consisting of women who tested negative for this PV (
N = 160) several months after receipt of the genetic test result (median 22, range 4–27). A total of 156 women (69%) returned the questionnaire; 52 cases (80%) and 104 controls (65%) on average 21 months after receiving the genetic test results (Table
2). The educational level of responding cases and controls did not differ significantly.
Table 2
Characteristics respondents questionnaire
Mean age at time questionnaire (min-max) | 59.40 (43–78) | 59.75 (31–84) | 59.63 (31–84) |
Country of origin (1 missing value) |
Netherlands | 52 | 100 | 152 |
Other (Indonesia, Israël, Marocco) | 0 | 3 | 3 |
Mean time gap test result and questionnaire | 19 months | 22 months | 21 months |
Median (min – max) | 21 (4–26) | 23 (10–27) | 22 (4–27) |
| N | % | N | % | p-value |
Education |
Low | 4 | 7.7% | 16 | 15.7% | n.s. |
Intermediate 1 | 19 | 36.5% | 23 | 22.5% |
Intermediate 2 | 16 | 30.8% | 27 | 26.5% |
High | 13 | 25.0% | 36 | 35.3% |
No breast cancer | 3 | | 5 | | |
Breast cancer | 49 | | 99 | | |
Unilateral | 37 | 75.5% | 84 | 84.8% | n.s. |
Bilateral | 12 | 24.5% | 15 | 15.2% | |
Perceived health |
Excellent/good | 45 | 86.5% | 85 | 81.7% | |
Moderate | 6 | 25.0% | 18 | 17.3% | n.s. |
Bad | 1 | 1.9% | 1 | 1.0% | |
Childless | 8 | 15.4% | 12 | 11.5% | n.s. |
Offspring | 44 | 84.6% | 92 | 88.5% |
N daughters | 57 | | 106 | |
N sons | 41 | | 101 | |
Most respondents had children (84.6% of cases and 88.5% of controls).
CHEK2 PV carriers were more often diagnosed with bilateral breast cancer than non-carriers (24.5% versus 15.2%), but the difference was not statistically significant (see Table
2).
Regardless of the results of the PV testing, almost all participants appreciated being recontacted for additional testing (98.1% of PV carriers and 95.2% of non-carriers) (Table
3). More counselees in the PV group (11.5%) tended to experience feelings of anxiety compared to those of the control group (5.8%), and recontacting was more frequently related to concerns about cancer in the family (15.4% for PV carriers versus 1.9% for non-carriers,
p < 0.001).
Table 3
Questions regarding the experiences with recontacting for the additional CHEK2 mutation test
Questions regarding recontacting | N | % | N | % | p-value |
Recontact appreciated |
agree | 51 | 98.1% | 99 | 95.2% | n.s. |
neutral | 1 | 1.9% | 5 | 4.8% |
disagree | 0 | 0.0% | 0 | 0.0% |
Recontacting caused a lot of anxiety for myself |
agree | 6 | 11.5% | 6 | 5.8% | n.s. |
neutral | 12 | 23.1% | 12 | 11.7% |
disagree | 34 | 65.4% | 85 | 82.5% |
Recontacting increased my worries for the family |
agree | 8 | 15.4% | 2 | 1.9% | < 0.001 |
neutral | 17 | 32.7% | 4 | 3.9% |
disagree | 27 | 51.9% | 97 | 94.2% |
Written information sufficient for informed decision |
agree | 50 | 96.2% | 99 | 96.1% | n.s. |
neutral | 1 | 1.9% | 3 | 2.9% |
disagree | 1 | 1.9% | 1 | 1.0% |
The decision for additional CHEK2 genetic testing was difficult |
agree | 2 | 3.8% | 2 | 1.9% | n.s. |
neutral | 3 | 5.8% | 7 | 6.7% |
disagree | 47 | 90.4% | 95 | 91.3% |
Difficult to determine advantages and disadvantages of additional testing |
agree | 5 | 9.6% | 8 | 7.7% | n.s. |
neutral | 7 | 13.5% | 20 | 19.2% |
disagree | 40 | 76.9% | 76 | 73.1% |
After receiving the CHEK2 test results | | | | | p-value |
The results of the test were as expected |
agree | 15 | 28.8% | 39 | 39.0% | 0.004 |
neutral | 19 | 36.5% | 49 | 49.0% |
disagree | 18 | 34.6% | 12 | 12.0% |
In retrospect I felt satisfied with having the choice for CHEK2 PV testing |
agree | 51 | 98.1% | 97 | 96.0% | n.s. |
neutral | 1 | 1.9% | 4 | 4.0% |
disagree | 0 | 0.0% | 0 | 0.0% |
The test results influenced cancer worries counselee |
no change in cancer worries | 35 | 67.3% | 89 | 88.1% | < 0.001 |
yes, increase of cancer worries | 14 | 26.9% | 1 | 1.0% |
yes, decrease of cancer worries | 3 | 5.8% | 11 | 10.9% |
The test results influenced cancer worries family members |
no change in cancer worries | 22 | 42.3% | 81 | 80.2% | < 0.001 |
yes, increase of cancer worries | 27 | 51.9% | 0 | 0.0% |
yes, decrease of cancer worries | 3 | 5.8% | 20 | 19.8% |
Regrets about the choice for additional genetic testing |
disagree | 52 | 100.0% | 103 | 99.0% | n.s. |
neutral | 0 | 0.0% | 1 | 1.0% |
agree | 0 | 0.0% | 0 | 0.0% |
Satisfaction with recontacting |
good | 51 | 98.1% | 103 | 99.0% | n.s. |
fair | 1 | 1.9% | 1 | 1.0% |
poor | 0 | 0.0% | 0 | 0.0% |
Satisfaction with information prior to DNA-test |
good | 46 | 88.5% | 97 | 97.1% | n.s. |
fair | 4 | 7.7% | 3 | 2.9% |
poor | 2 | 3.8% | 0 | 0.0% |
Satisfaction with information after test results |
good | 49 | 94.2% | 97 | 93.3% | n.s. |
fair | 3 | 5.8% | 7 | 6.7% |
poor | 0 | 0.0% | 0 | 0.0% |
Almost all women reported that the written information was sufficient to make an informed decision about the additional CHEK2 testing (96.2% of the PV carriers and 96.1% of the non-carriers), and slightly less PV carriers were satisfied with the written information that was provided prior to the DNA-test (88.5% of the PV carriers and 97.1% of the non-carriers).
A significant difference was found in the expected outcome of the DNA-test between PV carriers and non-carriers: 34.6% of the PV carriers did not expect the outcome of the test result versus 12.0% of the non-carriers (p = 0.004). After disclosure of the test results, the carriers had significantly more cancer worries than the controls, not only for themselves (26.9% carriers versus 1.0% controls, p < 0.001), but also for their family members (51.9% versus 0.0%, p < 0.001).
Discussion
To our knowledge, this study includes the largest group of patients recontacted for additional PV testing on newly identified cancer predisposition genes reported so far. As the genetics department of the UMC Utrecht had in the past suggested in the results letter to counselees with a negative BRCA1/2 test that further genetic testing would be done if deemed possible, we felt an obligation to actively recontact these women. This decision was also made in view of the frequent occurrence of the CHEK2 c.1100del PV in the Dutch population and the possible clinical implications.
With our approach we identified 66 carriers of the
CHEK2 PV, of whom 64 had been previously diagnosed with breast cancer at a relatively young age (mean age at diagnosis was 49 years). For reference, the mean age of breast cancer diagnosis in the general population in the Netherlands is 61 years [
19]. For proven female
BRCA1 and
BRCA2 PV carriers in the Netherlands, the mean ages of diagnosis are 40 years and 44 years respectively [
20]. Other clinical characteristics (receptor status) of the identified PV carriers are in line with previous finding [
21,
22].
Although the advantages and disadvantages of recontacting counselees for additional genetic tests have been described earlier, there are no recommendations or policies as of yet [
23,
24]. In general, there is a lack of consensus about when and whether a genetic counselor has a duty to recontact patients upon the availability of tests for newly discovered genetic PVs [
23‐
25]. Practical obstacles to recontacting are the feasibility of such an effort, including out-of-date contact information and limited resources, both in capacity and financially. On the other hand, recontacting patients may have important implications for these patients and/or their family members regarding their health, lifestyle choices and psychosocial well-being [
26].
When considering recontact, we had to take into account that genetic counselling of patients and family members from
CHEK2 PV families is challenging for several reasons. The risk estimates published thus far are based on limited data and might not be very accurate yet. Furthermore, for counseling purposes relative risks have to be translated into absolute risks and more age-specific risk estimates are needed but not yet available [
5]. For instance, it has been suggested that the breast cancer rate ratio declines with age for this PV [
3]. Also, increased risks for other malignancies besides breast cancer are reported as part of the tumor spectrum [
27‐
30]. As
CHEK2 is now part of a multigene panel for testing of breast cancer patients, more accurate risk estimates for breast cancer and other phenotypic information will become available in the near future. In the Netherlands a nationwide study recently started that will address the risk prediction, screening and therapy of breast cancer in women from
CHEK2 c.1100del families. This study is part of the Hereditary Breast and Ovarian cancer study Netherlands [
31].
The uptake of genetic testing in our recontacted counselees was higher than that earlier reported by Romero et al., who recontacted patients with medullary thyroid carcinoma and pheochromocytoma or paraganglioma for additional genetic testing [
32]. Chadwell et al. have reported that, in general, the cost of testing and insurance coverage might be the most important barriers to additional genetic testing [
33]. In our study the genetic test was done free-of-charge and the visit to the genetics department for the PV carriers was covered by the participant’s health insurance. Our high response rate may also be due to the fact that it took relatively little effort for participants to return the informed consent form and the reply form stating that they opted for additional PV testing. Even the drawing of blood was not necessary because DNA-material was still available.
There was a concern about the potential negative psychosocial consequences of our approach as women may not want to be reminded of their illness and of the consequences the test results might have for herself and her family members [
23,
25,
34]. Giesbertz et al. (2019) suggested that practical guidelines are needed to weigh the arguments in favor or against recontacting [
23]. Our findings suggest that the women recontacted for additional genetic testing appreciated our effort and that the written information was sufficient to make an informed decision about the additional
CHEK2 testing regardless of the test result and the possible anxiety it caused. This is an important finding in the light of the rapid developments within DNA-diagnostics, as it is conceivable that additional genetic testing on newly identified cancer predisposing genes will be offered more often in future.
An important limitation in our study is that the questionnaire on the impact of our approach comprises only a small sample (n = 104) of the 1600 non-carriers opting for the additional test. Furthermore, we do not have survey data on counselees who declined additional genetic testing. These women might have experienced our recontacting differently and perhaps had serious objections to an additional genetic test. A major limitation is that the questionnaire was sent after all additional CHEK2 testing was finished. Since it took us 2 years to recontact and test all eligible women there was a gap (on average 21 months) for some participants between the receipt of the test results and the completion of the questionnaire, and this might have affected the answers to our questions.
For the most part, the counselees who opted for additional
CHEK2 testing considered the written information provided sufficient to decide about genetic testing. Our findings give an important message to health care professionals, such as gynecologists, medical oncologists and breast surgeons, as they will increasingly deliver treatment-focused genetic testing as part of mainstream breast cancer care [
35].
Conclusions
In this study we assessed the uptake and patients’ experiences of recontacting a large number of women who had previously tested negative for
BRCA1/2 PVs for additional
CHEK2 testing. The uptake of our offer to perform
CHEK2 testing was high (70%), and the PV detection of 4% was in line with previous findings [
3,
10]. No patients with a homozygous
CHEK2 PV were found.
Overall the women who filled out the questionnaire were positive about the effort taken to approach them for additional testing for the CHEK2 PV. Despite the fact that the PV carriers more often experienced cancer worries and anxiety after the test result was revealed, the benefits of our approach seemed to outweigh the psychosocial burden. In fact, eight respondents specifically stated in the comments box at the end of the questionnaire, that they would like this approach to be a routine course of action in future.
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