Abstract
purpose. To investigate the very long-term prognosis of patients with uveal melanoma and the clinical characteristics influencing it.
methods. Charts, registry data, and histopathologic specimens of 289 consecutive patients with choroidal and ciliary body melanoma treated in the district of the Helsinki University Central Hospital, Finland, between 1962 and 1981 were audited. Definitions for coding the cause of death were adapted from the Collaborative Ocular Melanoma Study (COMS). Competing risks were taken into account by using cumulative incidence analysis and competing risks regression.
results. Of the 289 patients treated, 239 were deceased at the end of follow-up. The audited cause of death was uveal melanoma in 145 (61%) of them. The median follow-up of the 50 survivors was 28 years. The original histopathologic diagnosis of metastasis and second cancer was correct in 91% of all specimens, but immunohistochemical reassessment changed 10% of biopsy and 7% of autopsy diagnoses. Of 45 positive autopsies, 18% were performed without suspicion of melanoma. Uveal melanoma–related mortality was 31% (95% confidence interval [CI], 26–37) by 5 years, 45% (95% CI, 40–51) by 15 years, 49% (95% CI, 43–55) by 25 years, and 52% (95% CI, 45–58) by 35 years, according to cumulative incidence analysis. Of patients who died of uveal melanoma, 62%, 90%, 98%, and 100% did so within 5, 15, 25, and 35 years, respectively. Between 15 and 35 years, 20% to 33% of deaths were still due to uveal melanoma. By competing risks regression analysis, the hazard ratio was 1.08 (P = 0.0012) for each millimeter increase in tumor diameter, 2.27 (P = 0.0076) for extraocular growth, and 1.89 (P = 0.0011) for ciliary body involvement.
conclusions. Metastatic uveal melanoma was the leading single cause of death throughout the study. Cumulative incidences provide a sound basis for patient counseling and design of trials.
Malignant melanoma of the uvea disseminates purely hematogenously, unless it perforates the sclera and infiltrates the conjunctival lymphatics.
1 2 Local recurrence is infrequent, but this cancer often metastasizes before it is diagnosed.
3 4 5 In fact, approximately 50% of patients with uveal melanoma are thought to die within 10 years after diagnosis, irrespective of the type of treatment.
6
Several case reports describe supposedly unusual malignant uveal melanomas that showed clinical metastasis more than 20 years after enucleation.
7 8 9 10 These isolated reports cannot be used to quantitate the frequency of such a very late appearance of progressive metastasis. Few studies report survival data beyond 15 years, and the number of patients who remain under review at that time typically is low.
11 12 13 14 15 16 17 In published Kaplan-Meier curves of melanoma-related mortality, latest deaths tend to occur between 10 and 18 years after diagnosis.
11 18 19
The reasons for the scarcity of long-term survival data are that patients with uveal melanoma are mostly middle-aged or older, their life expectancy may be limited because of other illnesses, follow-up data of patients treated long ago are difficult to collect, the founding of national cancer registries is fairly recent, and patients may be difficult to trace long after treatment.
We determined the very long-term prognosis, defined as survival 15 years or more after treatment of a primary choroidal and ciliary body melanoma, in a consecutive series of patients from a defined region. Cause of death was audited by using cancer registry data and the patients’ charts and by immunohistochemical restaining of histopathologic specimens. We also tested statistically the sufficiency of follow-up to conclude whether cured patients were present in the data set. Cumulative incidence analysis and competing risks proportional hazards regression were used to estimate survival proportions most relevant for counseling of patients, most of whom are currently managed conservatively without access to histopathology.
Eligible for analysis in the study were patients who had choroidal and ciliary body melanoma managed a minimum of 20 years earlier. Iris melanomas were ineligible. This investigation was approved by the Institutional Review Board and adhered to the tenets of The Declaration of Helsinki.
Files of the Ophthalmic Pathology Laboratory, Department of Ophthalmology, Helsinki University Central Hospital, were searched from May 1962, when it was founded, to December 1981, to enroll all consecutive patients who underwent enucleation or exenteration. During this period, radical surgery was standard treatment for all but the smallest melanomas, which were observed for growth, and all eyes removed in the district were submitted to this laboratory. Two tumors diagnosed at autopsy and one rediagnosed as a nevus were excluded. Largest basal tumor diameter (LBD) and tumor height were measured from the sections or recorded from pathology reports.
A total of 240 patients had died by December 31, 2001. Complete data for all patients, except one whose identity could not be verified, were obtained from the Finnish Population and Cancer Registries and all hospitals and histopathology laboratories that had participated in management of uveal melanoma, its metastases, and other malignant tumors. Data for one patient who had emigrated was tracked manually. Records concerning terminal illness were obtained. Death certificates and histopathologic specimens were evaluated by consensus of two investigators to ascertain whether metastatic melanoma was present.
Definitions from the Collaborative Ocular Melanoma Study (COMS) were adapted.
20 21 If a specimen represented melanoma metastasis by review or it could not be retrieved but the original report unquestionably mentioned moderate to heavy melanin or HMB-45 immunopositivity, the code was “dead with melanoma metastasis (confirmed metastasis).” If the report did not mention either characteristic or if only a fine-needle aspiration biopsy had been performed and clinical findings (e.g., hepatomegaly, elevated liver function tests, and abnormal liver imaging) were consistent with hepatic metastases, the code ended “suspected melanoma metastasis.” If the death certificate specified melanoma, but clinical data were uninformative or the diagnosis was other than cancer when symptoms and clinical findings were consistent with hepatic metastases, it ended “possible melanoma metastasis.”
If a specimen represented another malignancy by review, the code was “malignant tumor present, not metastatic melanoma (confirmed second cancer).” If there was evidence of a second primary cancer and the clinical course did not suggest hepatic metastasis, the coding ended “suspected second cancer,” and if the death certificate specified other cancer but clinical data were uninformative it ended “possible second cancer.”
The code was “no evidence of malignancy (confirmed nonneoplastic disease)” if the autopsy revealed no cancer. If the death certificate specified disease other than cancer, the patient was not registered in the cancer registry for a second cancer, the patient’s charts were consistent with the given diagnosis, and liver imagining and liver function test results or both were normal within 6 months before death, the code ended “suspected nonneoplastic disease.” If neither test had been conducted within 6 months of death, the code ended “possible nonneoplastic disease.” “Insufficient evidence to establish presence of malignancy” was used if original charts could not be retrieved.
Analyses were performed on computer (Stata, ver. 7.0; Stata Software, College Station, TX, and R, ver. 1.4.0; available at http://www.r-project.org/ provided by The R Foundation for Statistical Computing, Vienna, Austria) software. All probabilities were two-sided, and P < 0.05 was considered significant.
Univariate analysis of survival was based on the cumulative incidence method, which appropriately handles failures from competing risks.
22 This is mandatory when long-term survival is evaluated, because competing events increase with follow-up as patients become older. In the calculation of cumulative incidence, only patients alive at the study’s termination and those lost to follow-up were censored.
22 We estimated mortality related to melanoma, second cancer, and nonneoplastic disease. Cumulative incidence between categories was compared with the Gray’s K-sample test.
23 Age was divided in quartiles and LBD in three categories (<10, 10–15, and ≥16 mm).
For comparison, the Kaplan-Meier estimate
24 of melanoma-related mortality was calculated. In the calculation of the Kaplan-Meier estimate, patients who die of unrelated causes are also censored. Deaths that occur after the first competing risk event contribute more to the estimate than is appropriate, and the melanoma-related mortality is overestimated.
22 The magnitude of the discrepancy depends on the timing and number of competing risk events. Survival curves were plotted to show mortality rather than survival to ease comparison with cumulative incidence.
24
Evidence for the presence of cured (“immune”) patients in the data was tested according to Maller and Zhou.
25 26 The null hypothesis was that there are no cured patients. Reverse censoring suggested that censoring distribution was uniform, and the corresponding statistical Table A.2 was used.
25 If the null hypothesis is rejected, cured patients either are present or follow-up is insufficient to be decisive.
25 The sufficiency of follow-up was tested by the q
n test of Maller and Zhou,
25 26 which is based on the distance between the largest censored and uncensored failure time. Both tests are nonparametric and make no assumption of the type and shape of the survival distribution.
25 27
Multivariate analysis of melanoma-related survival was based on competing risks proportional hazards regression.
28 Because cumulative incidence analysis suggested that mortality would not differ within the two lowest and two highest age quartiles, age at diagnosis was dichotomized according to its median. Tumor dimensions were modeled as continuous variables. Models were compared with each other by using the deviance test.
29
For comparison, the hazard rate (HR) was calculated by using the more commonly applied Cox proportional hazards regression,
30 in which melanoma-related deaths after the first competing risk event contribute more to the statistics than is appropriate.
A surgical or core needle biopsy to diagnose metastases or second primary cancer was performed in 77 (27%) patients. The original report identified 54 (70%) as melanoma metastases, 22 (29%) as second cancer, and 1 (1%) as nonneoplastic. Autopsy was performed in 70 (29%) of the 239 deceased patients. According to the autopsy report, 25 (36%) died without malignancy. Metastatic melanoma was recorded in 42 (60%) and second cancer in 3 (4%) autopsies.
Reassessment of 60 biopsy specimens showed the diagnosis to be incorrect in 6 (10%; 95% CI, 8–29). Five were amelanotic, epithelioid cell melanoma metastases to the liver and not hepatocellular and metastatic colonic carcinoma, and one was an anaplastic glioma. The diagnosis in 3 (7%; 95% CI, 1–18) of 45 autopsies in which a malignancy was found was incorrect. One presumed cholangiocarcinoma was in fact metastatic uveal melanoma and two presumed melanoma metastases were misdiagnosed metastatic mucocellular and anaplastic carcinoma of unknown origin.
Of 40 autopsies in which metastatic uveal melanoma was confirmed, 7 (18%; 95% CI, 7–33) were performed without suspicion of melanoma metastasis (e.g., because of presumed cerebrovascular accident, renal failure after hip surgery, and second cancer). This represented 10% (95% CI, 4–20) of all autopsies and 5% (95% CI, 2–10) of all deaths due to uveal melanoma.
The Kaplan-Meier method progressively exaggerated melanoma-related mortality by 5, 7, and 10 percentage points at 15, 25, and 35 years, respectively (
Fig. 2A ,
Table 2 ). The cumulative incidence estimate increased until 34 years from surgery to 45% (95% CI, 40–51) by 15 years, 49% (95% CI, 43–55) by 25 years, and 52% (95% CI, 45–58) by 35 years (
Fig 2B ;
Table 2 gives the corresponding survival estimates). Cured individuals may have been present among survivors (
P < 0.01), but the odds leaned toward insufficient follow-up (
P > 0.10,
Table 3 ).
Of the 145 patients who died of uveal melanoma, 62% (95% CI, 54–70) did so within 5 years, 80% (95% CI, 73–86) within 10 years, 90% (95% CI, 84–95) within 15 years, 98% (95% CI, 94–100) within 25 years, and 100% within 35 years (95% CI, 97–100).