The incidence of skin cancer is increasing throughout the world, making this disease the most common malignant neoplasm in Mexico.1 Basal cell carcinoma is the most frequent type (74%), followed by squamous cell carcinoma (14%), and melanoma (3%).2 The risk factors for skin cancer are chronic or intermittent sun exposure,3 history of sunburn,4 use of tanning beds,5 >15 melanocytic nevi,6 family and personal history of skin cancer, phototype (light-colored eyes and fair skin and hair),7 previous radiotherapy8 and phototherapy,9 immunosuppression associated with organ transplantation,10 and exposure to carcinogens such as arsenic (contaminated water).11

Skin cancer can be prevented by means of behavioral measures, such as avoiding sun exposure and using sunscreen, which are associated with an individual's perception of the risk of skin cancer. A perceived risk of cancer encourages preventive behavior, while the lack of such a perception is a barrier to risk reduction. It is well known that information cannot produce an expected effect on behavioral change, and that an individual's motivation to change his/her behavior is affected by social and psychological variables. The model developed by Jackson and Aiken to investigate the intention to protect oneself from the sun and to sunbathe brings together the theory of planned behavior,12 the health belief model,13 and the protection motivation theory.14,15 In the model, behavior associated with sun exposure is the result of 4 psychological variables: health beliefs, self-efficacy with respect to sun protection, attitudes toward sunbathing, and norms for protection and sunbathing. The intention of protecting oneself from the sun arises from an individual's perception of the risk of skin cancer, that is, those who feel threatened by or believe themselves prone to skin cancer will have the intention to protect themselves from the sun and avoid exposure to it.

According to Brewer et al,16 the perception of risk is a construct comprising 3 dimensions associated with the damage caused if measures are not taken to prevent it. The 3 dimensions are probability of damage, constitutional susceptibility or vulnerability, and severity or degree of damage. The perception of the risk of skin cancer is the impression or sensation of threat we feel based on individual severity, probability, and susceptibility, which are the product of the attitudes and beliefs towards the intention to protect oneself from and/or expose oneself to sunlight.17

Several methods have been applied to measure the perceived risk of melanoma and nonmelanoma skin cancer (basal cell and squamous cell carcinoma). The most common method involves measuring risk absolutely and comparatively, that is, by asking individuals to estimate their personal risk and their risk compared with the population in general, respectively. The absolute forms include those associated with and not associated with preventive behavior. They also include cognitive and affective-type measures of perceived risk; the former reflect the probability of having skin cancer based on the objective risk (norms), the latter reflect the purely cognitive component (beliefs). In summary, the dimensions of the construct for perceived risk of skin cancer are as follows: probability, susceptibility, severity, affective dimension, and behavioral dimension.15

No Spanish-language instruments have been developed to measure perceived risk of melanoma and nonmelanoma skin cancer. Some instruments evaluate behavior, attitudes, and knowledge associated with sun exposure. However, it is necessary to develop an instrument to measure perception of risk for use in future interventions to modify behavior with respect to sun exposure. The objective of the present work was to design and validate an instrument for measuring perceived risk of skin cancer (basal cell, squamous cell, and melanoma) in Mexicans aged >18 years. The instrument includes all 5 dimensions of the construct and is self-administered. The responses are given on a visual Likert-type scale of 7 options to make it easier to answer.

The instrument was administered to 359 patients at the Outpatient Clinic of Centro Dermatológico Dr. Ladislao de la Pascua in March and April 2012. The demographic characteristics of the sample were as follows: 70.2% women and 29.8% men, with a mean (SD) age of 38 (14.4) years. Educational level was primary in 18.4% of cases, secondary in 22%, university preparatory in 34.5%, undergraduate in 22.6%, and postgraduate in 2.5%.

Of the 60 initial items on the questionnaire, replies were provided for each of the 7 options on the pictorial Likert scale. Items 1, 4, and 18 were not discriminatory and were eliminated. Items 6-12, 17, 19-20, 31-36, 38-44, 52, and 56-60 were eliminated owing to lack of directionality. Item 22 was the only one with a correlation with the total <0.30, whereas 28, 30, and 46 had a squared multiple correlation <0.40. A high correlation was recorded between items 14, 16, and 21 and items 13, 15, and 25, respectively, (r=0.803, 0.883, and 0.815). Those with the best profile were selected, and items 13, 15, and 25 were eliminated. Table 4 presents the results for the correlations and the Cronbach α of those items that proved to be discriminatory and have directionality. A total of 39 items were eliminated; the Cronbach α or reliability of the instrument with the 21 items selected was 0.851. The factor analysis with orthogonal rotation was subsequently performed using the principal components method, since the correlations between the items were low to medium. Coefficients <0.40 were excluded. According to the percentage of variance explained and the break in the scree test, 5 real factors were identified. Items 21, 37, and 47 were repeated in more than 1 factor with factor weights >0.40; therefore, they were eliminated. Finally, 18 items remained, and the total Cronbach α was 0.824. Four factors (affective aspects, behavioral aspects, severity, and susceptibility) and an indicator of risk accounted for 65.133% of the variance. Table 5 shows the factors, their items, and the explained variance.

Each item has 7 possible options for response, with a minimum score of 1 and a maximum of 7 per question. Since the final questionnaire has 18 items, the minimum score is 18 and the maximum 126.

The linear standard qualification according to the z values showed that the mean (SD) total punctuation of the sample was 83.0529 (19.96225), whereas the median was 81 points with an interquartile range of 28 points. These findings enable us to interpret the results in subsequent applications of the questionnaire by comparing the final score with that obtained by our study sample, from which we obtained the norm for standardization.

The instrument is enclosed as an appendix.

The validated questionnaire enables us to measure the construct perceived risk of skin cancer. No specific instruments have been designed to measure this construct. Perceived risk of skin cancer has been investigated using focus groups and interviews.18 Questionnaires used at population level, such as the Health Information Trends Survey, measure the perceived risk of cancer by posing 3 questions associated with the probability of having skin cancer in the affective dimension.19 Bränström et al.21 measured the perceived risk of skin cancer using 3 questions on individual probability, the incidence of this type of cancer in Sweden, and the probability compared with another individual of the same age. However, the study by Janssen et al.17 compared the different forms of operationalization or design of questions for measuring this construct. The purpose-designed questionnaire comprised 14 and 13 questions from the dimensions of probability and severity, respectively. The results show us that the comparative and conditional questions are better predictors of sun protection behavior. The only available Spanish-language instrument is that of De Troya-Martín et al.,20 which measures knowledge and attitude associated with sun exposure; therefore, we consider that, to date, our questionnaire is the only one designed to measure perceived risk of skin cancer and that, together with the questionnaire of De Troya-Martin et al., it can be used to measure the impact of interventions aimed at preventing melanoma and nonmelanoma skin cancer.

The final version of the questionnaire is short (only 18 items) and easy to complete, since it is based on a pictorial scale. As with most psychometric instruments, it requires a cover sheet with instructions and trained staff to help with comprehension and completion. Unlike previous questionnaires, it measures the 5 dimensions of the construct perceived risk of skin cancer. Consistent with Janssen et al.,17 it was necessary to use structured items comparatively and conditionally; however, the dimensions of severity and probability only included items of absolute structure. The appearance and content validity of the instrument was achieved by having a representative set of items, which were formulated according to the bibliographic review, construct content sampling, author consensus, and the final review by an expert in the design and validation of psychometric instruments. In addition, we demonstrated the construct validity of the questionnaire using factor analysis, which made it possible to eliminate items that did not have the necessary profile. The consistency or internal reliability of the instrument is good, and we intend to apply temporal consistency tests such as test-retest. As this is an instrument that measures perceived risk, it is not absolutely necessary to measure internal reliability; however, internal consistency must be determined.

The main limitation of this instrument is that associated with the characteristics of the study sample. The sample chosen for validation of the instrument comprised patients attending a reference dermatology clinic in Mexico; most were women, and mean age was 38 years. In addition, the objective of our instrument was to measure perceived risk of skin cancer involving sun exposure, namely, basal cell carcinoma, squamous cell carcinoma, and melanoma, since prevention in these neoplasms focuses on avoiding risk behavior associated with sun exposure. However, there are other risk factors that, by their very nature, cannot be modified.

Perceived risk of skin cancer is an extremely useful measure in studies of clinical interventions to prevent skin cancer, since dissemination of information on skin cancer is not sufficient to ensure that preventive measures are adopted. Furthermore, it is essential that people realize that they are at risk of skin cancer so that they can modify their behavior with respect to sun exposure and protection.21 Therefore, improved perception of risk would be associated with behaviors aimed at sun protection. This is the reason why we propose that perceived risk be used to modify behavior and that the information provided to the general public and to high-risk groups should impact individuals in such a way that they perceive or identify the risk.

In summary, this validated Spanish-language questionnaire serves as a measurement tool in intervention studies on approaches to preventing skin cancer.

The authors declare that they have no conflicts of interest.