Breast cancer is a malignant tumour that develops in the mammary gland [1] .

Its incidence, already high in the 1970s, is still rising in both developed and developing countries [2] . Between 1975 and 2000, incidence rose by between 0.5% and 1.5% in many countries [3] . In Asia and China in particular, this increase has reached 3% to 5% per year over the last three decades [4] . In Europe, the highest levels of incidence are observed in Western European countries, in contrast to Eastern European countries [5] . In Africa, taking current trends into account, the number of new cases of breast cancer is expected to double by 2040 [6] .

Its management, particularly clinical management, requires high-quality, long-term medical care adapted to its chronic nature and metastatic potential. Among many prognostic factors, the clinical stage of the tumor at diagnosis is one of the most important determinants of post-treatment outcome, whatever the technical platform [7] . The average cost of this treatment, estimated at $1000 per patient every three weeks, represents a considerable financial burden for healthcare systems, patients and their families [8] , especially in developing countries. Since 2020, breast cancer has become the leading cause of cancer mortality worldwide [9] .

Faced with this problem, the international community, through the WHO, has observed that to guarantee women’s health in the face of breast cancer, the fight must be waged through two essential measures: mass screening and early diagnosis and treatment [10] :

- For mass screening, the standard tripod recommended is the clinical breast examination, combined with breast ultrasound and mammography [11] .

- As for early diagnosis and treatment, women should examine their own breasts regularly, and consult their doctor immediately in the event of any abnormality [12] .

Given that the first measure requires financial outlay for the acquisition of screening tools [8] , particular emphasis is placed on women’s effective participation in their own destiny in the face of breast cancer through the second measure, which entails no financial outlay. So far, however, this recommendation does not seem to have been fully taken on board, given the continuing high incidence of late-stage breast cancer at diagnosis, especially in developing countries.

In the DRC, breast cancer mortality is also high [13] . To explain this level of mortality, Espina C et al. [14] cite the late arrival of patients in the advanced stages of their disease, without saying whether this was due to ignorance or environmental obstacles, and deplore the limitations associated with care due to a rudimentary technical platform, precarious economic conditions and the absence of a health insurance system.

Several other studies on breast cancer have been carried out in the DRC, and numerous aspects have been addressed. However, to date, no study assessing the knowledge, attitudes and practices of Congolese women with regard to breast cancer is available, and is likely to justify their behavior in the face of this cancer, understand their late consultations and help refine strategies to reduce its mortality, even though the national strategic plan to combat cervical and breast cancers [15] deplores the lack of information on these two cancers since 2015.

Bearing in mind the above-mentioned characteristics, we felt it appropriate to initiate the present study with the aim of assessing the knowledge, attitudes and practices of Congolese women in Kinshasa regarding breast cancer.

Our cross-sectional descriptive study with analytical aims based on a mixed method (qualitative and quantitative) was conducted in the city of Kinshasa from June to September 2023.

Our sampling is of the 3-stage cluster probability type.

To minimize information bias, interviewers were recruited, trained, tested and selected based on their performance, a pre-test of the questionnaire was carried out, collection forms were checked daily by the person in charge of the survey, and incomplete or badly filled-in forms were discarded.

The sample size was calculated using the following formula:

$n\ge \frac{Z^{2}Pq}{d^2}$

n = minimum sample size.

Z = 1.96 (95% confidence coefficient).

P = 0.6 (proportion of women who performed breast self-examination).

d = 0.05 (degree of precision).

The sample size was 386 women. This sample size was increased by 30% to 499%.

However, to obtain as much information as possible and increase the accuracy of statistical tests, the sample size was increased to 1170 by interviewing at least one person meeting our inclusion criteria in each plot.

At the end of this survey, we recorded 1170 questionnaires which had fulfilled all the inclusion criteria. About socio-demographic characteristics ( Table 1 ), the average age of the respondents was 41.12 ± 14.59 years. The most numerous were those aged 50 or over (42.4%), with secondary education (57%), shopkeepers (39.2%), followers of revivalist churches (51.4%) and living in the Tshangu district (41%).

About level of knowledge, an analysis of Table 2 reveals that 60% are insufficiently knowledgeable.

Referring to the factors associated with insufficient knowledge, Table 3 shows that the factors most strongly and positively associated with insufficient knowledge are: residence in the Tshangu district (aOR = 5.92; IC 95% 3.48 - 10.39; p = 0.001), primary education (aOR = 3.71; IC 95% 2.20 - 6.34; p = 0.001), membership of revivalist churches (aOR = 2.40 IC 95% 1.43 - 4.07; p = 0.00), unemployment (aOR = 4.96; IC 95% 2.80 - 9.20; p = 0.001), nulliparity (aOR = 2.49; IC 95% 1.72 - 3.63; p = 0.001) and absence of breastfeeding (aOR = 1.668; IC 95% 1.237 - 2.249; p = 0.000).

In terms of attitudes, this study shows that 74.4% of respondents’ attitudes towards breast cancer were negative ( Table 4 ).

Table 5 shows that the factors most strongly and positively associated with negative attitudes are age < 30 years (aOR = 6.66; CI 95% 4.42 - 10.15; p = 0.001), living in Tshangu (aOR = 9.34; CI 95% 4.02 - 23.75; p = 0.001), primary education (aOR = 5.77; CI 95% 2.94 - 11.69; p = 0.001), belonging to the Muslim religion (aOR = 5.83; CI 95 2.83 - 10.25; p = 0.001), occupation as a farmer (aOR = 8.29; CI 95% 3.93 - 18.46; p = 0.001), nulliparity (aOR = 2.61; CI 95% 1.37 - 4.98; p = 0.003), absence of breastfeeding (aOR = 3.86; CI 65% 5.84 - 36.85; p = 0.001) and insufficient knowledge of breast cancer (aOR = 3.98; CI 95% 2.43 - 5.48; p = 0.001).

80% of respondents’ breast cancer practices were non-beneficial ( Table 6 ).

With regard to factors associated with non-beneficial breast cancer practices, Table 7 shows that the factors most strongly and positively associated with respondents’ non-beneficial breast cancer practices are secondary education (aOR = 2.06; 95% CI 1.33 - 3.21; p = 0.001), membership of revivalist churches (aOR = 2.69, CI 95% 1.04 - 3.18, p = 0.038), nulliparity (aOR = 5.91, CI 95% 2.08 - 10.7, p = 0.001), absence of sporting activities (aOR = 1.51; CI 95% 1.33 - 1.69; p = 0.000) and insufficient knowledge of breast cancer (aOR = 1.64; CI 95 1.15 - 2.33; p = 0.006).

Using a descriptive study with an analytical aim applied to a sample of 1170 respondents selected by a 3-stage cluster sampling in the city province of Kinshasa, the results obtained allow us to draw the following conclusions:

- There is a great diversity of knowledge, attitudes and practices regarding breast cancer among Congolese women in Kinshasa.

- Despite this diversity, this knowledge is erroneous at 60%, attitudes are negative at 75% and practices are not beneficial at 80%.

All authors contributed to the design, collection and analysis of data as well as the presentation of the final manuscript.