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Epidemiology of melanoma in Puerto Rico, 1987-2002.

Resumen

La incidencia de melanoma cutaneo continua una tendencia de aumento a traves del mundo reflejando el mayor aumento de todas las malignidades en las ultimas decadas. Las tasas de mortalidad para melanoma se han mantenido relativamente estables en la mayoria de los paises a pesar del aumento en las tasas de incidencia.

El proposito de este estudio es describir las tendencias epidemiologicas de melanoma en Puerto Rico entre el ano 1987 y el 2002 y comparar los hallazgos con aquellos datos previamente reportados para Puerto Rico como para otros paises.

Todos los casos de melanoma reportados al Registro de Cancer de Puerto Rico entre el 1987 y el 2002 se incluyeron en el analisis. Se calcularon las tasas de incidencia y mortalidad ajustadas por edad. Las tendencias se compararon por edad, genero, localizacion anatomica del tumor y grosor del tumor.

Se reportaron un total de 1,568 casos nuevos de melanoma entre el 1987 y el 2002, lo que constituye un 50% de aumento en incidencia durante este periodo. La razon de hombres a mujeres fue de 1:1. La localizacion anatomica mas comun en mujeres fue la extremidad inferior seguido del area de la cabeza y cuello. En los hombres, la localizacion anatomica mas comun fue el tronco seguido de la cabeza y cuello. La mayoria de los tumores superficiales (<1mm) se encontraban en el tronco seguido de la extremidad inferior. El diagnostico histologico especifico mas comunmente reportado fue "melanoma in situ." En 40.82% de los casos el grosor del tumor no fue reportado. El numero de melanomas finos (<1mm) reportados aumentaron anualmente durante el periodo de estudio. Las tasas de mortalidad fueron levemente mayores en los hombres que en las mujeres, sin embargo, las mismas se mantuvieron estables para ambos generos y grupos de edades analizados.

En conclusion, las tasas de incidencia de melanoma continuan aumentando en Puerto Rico. Esto, en combinacion con un aumento en el diagnostico de melanomas superficiales, sugiere que la estabilizacion en las tasas de incidencia se debe en gran parte, a un diagnostico mas temprano y por consiguiente un mejor pronostico.

Background: The incidence of cutaneous malignant melanoma continues an increasing trend worldwide and has had the highest rise in incidence of all malignancies during the last decades. Mortality rates for melanoma have remained relatively stable in most countries despite the increase in incidence rates. The purpose of this study is to describe the epidemiological trends of malignant melanoma in Puerto Rico from 1987 to 2002 and to compare these findings with those previously reported for Puerto Rico as well as with those reported for other countries.

Methods: All cases of malignant melanoma reported to the Puerto Rico Cancer Registry from 1987 to 2002 were included. Age-adjusted incidence and mortality rates were calculated. Trends were compared by age, gender, anatomical location of the tumor and tumor thickness.

Results: There were 1,568 new melanoma cases reported between 1987 and 2002 in Puerto Rico, comprising a 50% overall increase in incidence during this period. Male to female incidence ratio was 1:0.86. The most common anatomical location in women was the lower extremity followed by the head and neck region. In men, the most common anatomical location was the trunk, followed by the head and neck region. Most of the superficial tumors (<1mm) were located on the trunk followed by the lower limb. The most common specific histologic diagnosis reported was melanoma in situ. In 40.8% of the cases the tumor thickness value was not provided. The number of thinner melanomas (<1mm) reported increased during the study period. Mortality rates were slightly higher for men than for women, still mortality rates remained stable for both genders and all age groups analyzed.

Conclusions: Melanoma incidence rates continue to increase in Puerto Rico. This, in combination with an increase in the diagnosis of thin melanomas, suggests that the stable mortality rates may be due, in part, to earlier diagnosis and improved overall prognosis.

Key words: Melanoma, Incidence, Puerto Rico.

**********

Malignant melanoma (MM) is primarily a malignancy of white individuals. It is currently the seventh most common cancer in the United States and it is the most common cancer in women aged 25 to 29 years old (1). Although it is accounts for only 4% of all skin cancers, it is responsible for more than 77% of all skin-cancer related deaths.

The incidence of melanoma continues an increasing trend worldwide, with the highest incidences being in Australia and New Zealand (2). Incidence rates in the United States have tripled in the white population during the last 20 years. Currently, the expected lifetime risk for developing invasive melanoma is one case per sixty Americans, a 2000% increase since 1930 (1). The annual percent change (APC) based on rates age-adjusted to the 2000 US Standard population for the period from 1995 to 2004 for white males and females was 2.3 (3). The prevalence of MM in Hispanic persons is approximately one sixth of that of white persons. The incidence rate per 100,000 (age-adjusted to the 2000 US Standard population) for White Non-Hispanics was 25.1, 4.5 for Hispanics, and 1.0 for Blacks in the United States during 2000-2004 (3). The mortality rates per 100,000 (age-adjusted to the 2000 US Std population) for White Non-Hispanics was 3.2, and 0.7 for Hispanics while it was only 0.4 for Blacks during that same period (3).

Although the incidence of melanoma has risen at the fastest rate of all malignancies during the last decades (4), mortality rates have remained generally stable worldwide, particularly among younger age groups (5-7). An increase in the diagnosis of thin melanomas has also been observed recently in some countries (6-7), including Puerto Rico (8).

The purpose of this study is to describe the epidemiological trends of malignant melanoma in Puerto Rico from 1987 to 2002 and to compare these findings with those previously reported for Puerto Rico (9-10) and as well as with those reported for other countries.

Methods

All the cases of MM reported to the Puerto Rico Central Cancer Registry between 1987 and 2002 were reviewed. The data of each case included age and gender of the patients, year of diagnosis, anatomical location of the tumor, histologic subtype of the tumor and tumor thickness. The numbers of deaths from MM by age groups and gender for each year in the study period were also available for review. Age-adjusted incidence and mortality rates were calculated based on the Puerto Rico Census Bureau population estimates of the year 2000. Age-specific incidence and mortality rates were also calculated. The percent change in incidence over the study period was calculated by subtracting the average rates of the first two years from the average rates of the last two years. This difference was divided by the average of the rates in the first two years and then multiplied by 100 to obtain a percentage (11).

Results

There were 1,568 new cases of melanoma reported to the Puerto Rico Cancer Registry between 1987 and 2002. The annual number of cases reported ranged from 52 to 164 with a mean of 98 new cases per year. There were 756 (48.2%) male cases and 812 (51.8%) female cases. Ages ranged from 5 to 110, with a mean age at diagnosis of 60 years old. Annual age-adjusted incidence rates per 100,000 habitants raged from 1.9 to 3.6/100,000, with an overall increasing trend in incidence throughout the period studied (Figure 1). As can be observed in Figure 1, a dramatic increase in incidence during 1991 and 1992 was followed by a sharp decline. This trend can be partially explained by changes in the reporting procedures of the Puerto Rico Central Cancer Registry (PRCCR) during those years. Before 1993, the PRCCR followed an active protocol for the identification and documentation of cancer cases, which was then modified to a passive registry. In 1997 the PRCCR received a federal grant to update and collect missing cancer data; the corresponding effect can be observed in Figure 1 with the steady increase in incidence since 1997. (Personal communication with PRCCR's director).

The majority of the cases reported in both sexes were between the ages of 61 to 80 years old. Age distribution varied somewhat between males and females. (Table 1) Among males, 82% of melanoma cancer cases were between the ages of 41 to 90 years old, with an average age of 61 years. In women 74% of the cases were between the ages of 41 to 90 years old with an average age of 60 years.

The most common anatomical location overall was the head and neck region (n = 378), followed by the lower limb (n = 362) and the trunk (n = 360). Male cases were most frequently reported on the trunk (28%) followed by the head and neck (26%), while female cases were most commonly found in the lower limb (27%) followed by the head and neck region (22%). (Table 2) The percent distribution of anatomical sites by sex was statistically different (p < 0.0001).

There were some variations in the anatomical location of melanoma when examined by age groups as illustrated in Tables 3 and 4. In male patients less than 60 years of age, tumors were most commonly found in the trunk. In male patients 60 years or older most of the tumors were located on the head and neck region (31%) followed by the lower limb (24%). (Table 3) As can be observed in Table 4, the trunk was the most common anatomical site for females cases under 40 years of age at diagnosis. The limbs were frequent anatomical sites for females 40 to 60 years of ages: upper limb (27%) and lower limb (26%). The head and neck (28%) as well as the lower limb (28%) were preferred anatomical sites among females over 60 years of age. There were 19 melanoma cases reported occurring on the genitalia and they were all on females. Of these, 15 occurred in women older than 60 years of age.

Most of the melanomas whose tumor thickness was reported measured < 1mm. When comparing tumor thickness with anatomical location, most of the melanomas in situ were located on the trunk followed by the head and neck region. Melanomas that measured < 1mm were mostly located of the lower limb followed by the trunk.(Table 5) In 40.8% of the cases the tumor thickness was not reported. It is also important to mention that the number of diagnosis of thin tumors, or less than 1mm thickness, increased during the period studied, ranging from 14 to 100 cases per year and reaching 100 cases in 2002. When analyzing the percent of melanoma cases that measured < 1mm from 1997 to 2002, there was a 19% increase when comparing the periods from 1997-1998 and 2001-2002 (Figure 2).

The most common specific histologic diagnosis reported was melanoma in situ (22.3%) followed by lentigo maligna (9.3%), nodular melanoma (5.6%), superficial spreading melanoma (5.3%), lentigo maligna melanoma (4.7%), and acral lentiginous melanoma (4.6%). In 44.1% of the cases no specific histologic subtype was reported.

There were a total of 242 deaths reported secondary to melanoma during the period studied. Of these, 133 were in males and 109 were in females with a mean of 8 deaths per year for males and 7 deaths per year for females. Even though age-adjusted incidence rates increased during the period studied, overall age-adjusted mortality rates remained stable ranging from 0.3 to 0.7 per 100,000 habitants per year. (Figure 3)

Although mortality rates remained stable during the 16 years included in the study, mortality cases increased with advancing age groups. (Figure 4) Approximately 74% of the deaths reported occurred in patients older than 60 years of age. It is also important to note that in all age groups mortality cases were equal or slightly higher for men than for women except in patients older than 85 years, were female cases outweighed those reported for males.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Discussion

There was a total of 1,568 new melanoma cases in Puerto Rico from 1987 to 2002, with an average of 98 new cases per year. This value nearly doubled the average number of new cases of melanoma reported during 1977 to 1987, when there was an average of 45 new cases diagnosed per year (9-10). During the sixteen years included in the study period there was a 50% overall increase in melanoma incidence in Puerto Rico. This increase in incidence was due mostly to an increased incidence in patients between 40 and 60 years old (3.5 per 100,000 habitants in 1987 to 5.5 per 100,000 habitants in 2002). In patients younger than 40 years old and older than 60 years old, age-specific incidence rates remained stable during the study period.

When comparing incidence rates in Puerto Rico for the year 2002 with those of the United States and Australia, it is evident that in the latter, the incidence rates are much higher that those encountered in our island. Australia has the highest melanoma incidence in the world (11). Age adjusted incidence rate for melanoma in that country for 2002 was 38.5 per 100,000 habitants for men and 29.5 per 100,000 for women (11). The overall incidence rates in the United States have increased nearly 138% from 1975 to 2002 (7.9 per 100,000 to 18.6 per 100,000) with a disproportionate increase in persons over the age of 55 years (3). The annual percent change in the United States was +2.3 for the period of 1995-2004, which was statistically significant (p<0.05)(3). Incidence rate during 2002-2004 for white males was 31.4 per 100,000 and 4.5 per 100,000 for Hispanic males living in the United States (3). In Puerto Rico, the overall age adjusted (2000 Standard Puerto Rico Population) incidence increased from 2.3 to 3.5 per 100,000 when 1987-1988 rates are compared to 20012002 rates and the overall annual percent change was +3.1. Even though we cannot directly compare rates form Puerto Rico to the rates previously presented for the US population (SEER data) because they are not adjusted to the same standard population, the annual percent change can be compared. The annual percent change was +2.3 in the US (1995-2004) while it was +3.1 in Puerto Rico (1987-2002).

Mortality rates in our study remained stable throughout the years for both genders and all age groups, despite an overall increase in incidence. This is comparable with other countries where a stable mortality rate trend has been observed particularly in younger age groups, while mortality continues to rise in older patients. In the United States, an increase in mortality rates has been observed in men and women 65 years of age and older, with an increase of 130% and 73% for men and women, respectively, from 1973 to 2002 (3). In Australia increased mortality has also been noted in patients, of both genders, older than 80 years of age (11). Still, in our results, mortality rates increased with advancing age groups and were slightly higher for men that for women a finding also encountered in other countries such as Australia, New Zealand, United States, and the United Kingdom (11).

Another trend observed in our study was that of an increase in the number of thin (< 1mm Breslow) melanomas throughout the years in the study period, while melanomas thicker than 1mm remained stable. This increase in thin melanomas has also been reported in other countries. In Italy, the number of melanomas reported that were < 1mm in thickness increased significantly for both genders between 1987 and 2003 (12). In Australia, the percentage of melanomas in situ increased one third between 1991 and 2002 (5), while in the United States, there has been an increase in thin melanomas (< 1mm) in groups of patients younger than 65 years of age, but a continued increase in thick tumor in those older than 65 years of age (11).

An important finding in this study was that in 40.8% of the melanoma cases reported from 1987 to 2002, the Breslow value was not provided. Even though this is an improvement from the 89% of cases in which this value was not provided during 1977 to 1987 (9-10), it is a significant finding because tumor thickness represents the most important prognostic factor for melanoma.

A previous population based study (13) regarding epidemiological trends for melanoma in Puerto Rico, also obtained the data from the Puerto Rico Central Cancer Registry and included the incidence rates of melanoma from 1987 to 1991, a time period also included in our analysis. This study adjusted the incidence rates to the age distribution of the 1950 Puerto Rican standard population while our study adjusted the incidence rates to the age distribution of the 2000 Puerto Rican standard population, rates that are not directly comparable. The difference in both studies could be explained in part by the fact that the PRCCR was undergoing important changes during the time periods in which these two studies overlap.

In conclusion, although melanoma incidence rates continue to increase in Puerto Rico, the risk is less than in other regions such as Australia and the United States. Still, this increase in the incidence of melanoma in combination with an increase in the diagnosis of thin melanomas, suggest that the stable mortality rates may be due, in part, to earlier diagnosis and improved prognosis.

References

(1.) Jemal A, Siegel R, Ward E, et al. Cancer statistics, 2006. CA Cancer J Clin, 2007;57:43-66.

(2.) Ferlay J, Bray P, Pisani P, et al. GLOBOCAN 2000: Cancer Incidence, Mortality and Prevalence Worldwide, Version 1.0. IARC Cancer Base No.5. Lyon, IARC Press, 2001.

(3.) Ries LAG, Eisner MP, Kosary CL, et al. SEER Cancer Statistics Review, 1975-2002. Bethesda MD: National Cancer Institute; http://seer.cancer.gov/csr/1975_2002/.

(4.) Benova C, Sober AJ. Melanoma incidence trends. Dermatol Clin. 2002;20:589-95.

(5.) Hall H.I., Miller D, Rogers Jet al. Update on the incidence and mortality from melanoma in the United States. J Am Acad Dermatol. Jan. 1999;40:35-42.

(6.) Coory M, Baade P, Aitken J, et al. Trend for in situ and invasive melanoma in Queensland, Australia, 1982-2002. Cancer Causes Control. 2006;17:21-27.

(7.) Lasiothiotakis K, Leiter U, Gorkievicz R, et al. The Incidence and Mortality of Cutaneous Melanoma in Southern Germany: Trends by Anatomic Site and Pathologic Characteristics, 1976-2003. Cancer, 2006; 107(6): 1331-1339.

(8.) Gonzalez-Fernandez M, Sanchez J.L. Malignant Melanoma in Puerto Rico: an Update. PRHSJ, 1999;18(2):95-98.

(9.) Vazquez Botet M, Torres S, Sanchez J.L. Malignant Melanoma in Puerto Rico. Bol Asoc Med P. Rico. 1983;75(1):8-10.

(10.) Vazquez Botet M, Latoni D, Sanchez J.L. Melanoma Maligno en Puerto Rico. Bol Asoc Med P. Rico. 1990;82(10):454-57.

(10.) Ries LAG, Kosary CL, Hanckey BF, et al. SEER Cancer Statistics Review, 1973-1994. National Institutes of health Publication No. 97-2789. Bethesda (MD): National cancer Institute. 1997.

(11.) Giblin AV, Thomas JM. Incidence, mortality and survival in cutaneous melanoma. J Plast Reconstr Aesthet Surg. 2007;60(1):32-40.

(12.) Chellini E, Crocetti E, Carli P, et al. The melanoma epidemic debate: some evidence for a real phenomenom from Tuscany, Italy. Melanoma Research. 2007;17(2):129-130.

(13.) Matta J, Nazario C, Armstrong R, et al. Epidemiological trends of melanoma in Puerto Rico from 1975-1991. Bol Asoc Med P. Rico. 1998;90:8-11.

SHEILA M. VALENTIN, MD *; JORGE L. SANCHEZ, MD, MD [dagger]; LUZ D. FIGUEROA, MD [double dagger]; CRUZ M. NAZARIO, Ph D **.

* Second Year Resident, Department of Dermatology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico, [dagger] Professor, Department of Dermatology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico, [double dagger] Associate Professor, Department of Dermatology, University of Puerto Rico, School of Medicine, San Juan, Puerto Rico, ** Professor, Department of Bioestatistics and Epidemiology, University of Puerto Rico, School of Public Health

Address correspondence to: Luz D. Figueroa, MD, University of Puerto Rico, Department of Dermatology, PO Box 365067, San Juan, Puerto Rico 00936-5067, Tel. (787) 765-7950, Fax. (787) 767-0467, E-mail: rcmderrnatol@gmail.com
Table 1. Percent distribution of melanoma cancer cases in
Puerto Rico from 1987 to 2002 by age and sex.

Age (yrs)   Males              Females            Total

            Number   Percent   Number   Percent   Number   Percent

0-10        1        0.1       1        0.1       2        --
11-20       6        0.8       9        1.1       15       1
21-30       27       3.6       35       4.3       62       4
31-40       45       6.0       86      10.6       131      8
41-50       114     15.1       108     13.3       222      14
51-60       112     14.8       123     15.2       235      15
61-70       160     21.2       151     18.6       311      20
71-80       156     20.6       128     15.8       284      18
81-90       78      10.3       88      10.9       166      11
91-100      12       1.6       22       2.7       34       2
101-110     1        0.1       1        0.1       2        --
Unknown     44       5.8       60       7.3       103      7
Total       756      100       812      100       1568     100

Average ([+ or -]SD)

[Age.sub.male] = 61.2 [+ or -] 7.6

[Age.sub.female] = 59.5 [+ or -] 7.3

Table 2. Anatomical sites of melanoma cancer cases in Puerto Rico
from 1987 to 2002 by sex. Melanoma cancer cases were classified
into five categorical locations. There is a statistically significant
(p<0.0001) difference of anatomical location by sex.

                      Males             Females             Total

Anatomical      Number   Percent   Number   Percent   Number   Percent
Site

Head & Neck     196      26        182      22        378      24
Trunk           207      28        153      19        360      23
Upper limb      104      14        152      19        256      16
Lower limb      147      19        215      27        362      23
Genitalia       0        0         19       2         19       1
Not specified   102      13        91       11        193      13
Total           756      100       812      100       1568     100

[chi square] = 28.73, 3 d.f.; p<0.0001
([chi square] calculated excluding genitalia and not specified sites)

Table 3. Anatomical sites of melanoma cancer cases in males
in Puerto Rico from 1987 to 2002 by age groups.

                  [less than or
Male            equal to] 40 years      40-60 years
Anatomical
Site            Number    Percent   Number    Percent

Head & neck     8         10        46        21
Trunk           38        48        72        32
Upper limb      10        13        41        18
Lower limb      9         11        34        15
Genitalia       0         --        0         --
Not specified   14        18        32        14
Total           79        100       225       100

Male                >60 years            Unknown
Anatomical
Site            Number    Percent   Number    Percent

Head & neck     128       31        14        32
Trunk           90        22        7         16
Upper limb      46        12        7         16
Lower limb      99        24        5         11
Genitalia       0         --        0         --
Not specified   45        11        11        25
Total           408       100       44        100

[chi square] = 22.86, 3 d.f.; p<0.0001 comparing the anatomical
sites distribution among males, 40-60 years of age and those older
than 60 years of age. ([chi square] calculated excluding genitalia,
not specified sites and unknown age)

Table 4. Anatomical sites of melanoma cancer cases in females
in Puerto Rico

                  [less than or
Female          equal to] 40 years      40-60 years
anatomical
site            Number    Percent   Number    Percent

Head & neck     13        10        40        17
Trunk           45        34        48        21
Upper limb      21        16        63        27
Lower limb      38        29        59        26
Genitalia       2         2         2         1
Not specified   12        9         19        8
Total           131       100       231       100

Female               >60 years            Unknown
anatomical
site            Number Percent      Number    Percent

Head & neck     111       28        18        31
Trunk           47        12        13        22
Upper limb      60        15        8         14
Lower limb      111       28        7         11
Genitalia       15        5         0         --
Not specified   47        12        13        22
Total           391       100       59        100

[chi square] = 24.28, 3 d.f ; p<0.0001 comparing the anatomical
sites distribution among females, 40-60 years of age and those
older than 60 years of age. ([chi square] calculated excluding
genitalia, not specified sites and unknown age)

Tabla 5. Tumor thickness of cases of malignant melanoma in Puerto
Rico from 1987 to 2002 by sex

Anatomical site

Tumor       Head &      Trunk       Upper       Lower
thickness   neck                    limb        limb
(mm)

In situ     93          107         75          36
<1          99          125         93          172
1-1.99      6           6           5           8
2-3.99      3           1           4           5
e"4         5           2           1           6

Unknown                 640/        40.8%

Tumor       Genitalia   Not         Total
thickness               specified
(mm)

In situ     1           37          349/
                                    22.3%
<1          5           29          523/
                                    33.3%
1-1.99      1           0           26/
                                    1.7%
2-3.99      1           2           16/
                                    1.0%
e"4         0           0           14/
                                    0.9%
Unknown

2002 by anatomical site.

Figure 1. Annual age-adjusted incidence rates of malignant
melanoma in Puerto Rico Form 1987 to 2002.

Melanoma In PR, 1987-2002: Age-adjusted incidence rate

Incidence rates x 100,000

1987     2.7
1988     1.9
1989     1.7
1990     2
1991     3.3
1992     3.2
1993     1.7
1994     2.3
1995     2.2
1996     2.6
1997     2.3
1998     3
1999     2.8
2000     3.4
2001     3.3
2002     3.6

Note: Table made from bar graph.

Figure 2. Percent of cases of melanoma with Breslow <1mm
diagnosed in Puerto Rico form 1987 to 2002.

Percent cases of melanoma with Breslow <1mm in
Puerto Rico from 1997-2002

1997     51
1998     56
1999     67
2000     64
2001     66
2002     61

Note: Table made from bar graph.
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Title Annotation:ORIGINAL ARTICLES
Author:Valentin, Sheila M.; Sanchez, Jorge L.; Figueroa, Luz D.; Nazario, Cruz M.
Publication:Puerto Rico Health Sciences Journal
Date:Dec 1, 2007
Words:4233
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