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1From the Eye Pathology Institute, University of Copenhagen, Copenhagen, Denmark; the 2Department of Ophthalmology, Rigshospitalet, Copenhagen, Denmark; the 3Centre for Cancer Documentation, Department of Prevention and Documentation, Danish Cancer Society, Copenhagen, Denmark; and the 4Department of Experimental, Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark.
| Abstract |
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METHODS. All iris, ciliary body, and choroidal melanomas (N = 2758) examined between 1942 and 2001 at the Eye Pathology Institute, University of Copenhagen, Denmark, and the Institute of Pathology, Aarhus University Hospital, Aarhus, Denmark, were reviewed. Cases with optic nerve invasion were identified and subdivided into prelaminar or laminar invasion and postlaminar invasion. Clinical characteristics were compared with those from 85 cases randomly drawn from all ciliary body and choroidal melanomas without optic nerve invasion from the same period. Survival data were obtained by the Kaplan-Meier method, and the Mantel-Cox log-rank test was used to test differences in survival among the three patient groups.
RESULTS. Optic nerve invasion was found in 157 uveal melanomas (5.7%; 95% confidence interval [CI], 4.8%6.6%). Frequency varied during the observation period between 5% and 7%. Only choroidal and ciliary body melanomas were found to invade the optic nerve. Eighty-five (54%) were confined to the prelaminar or laminar part, and 72 (46%) were confined to the postlaminar part. Increased intraocular pressure (IOP) and juxtapapillary location were associated with prelaminar or laminar invasion and postlaminar invasion. Age older than 70 years, reduced vision to light perception or worse, nonvisible fundus, and large (>15 mm) tumor size were associated with postlaminar spread. In univariate analysis, patients with postlaminar invasion had significantly higher all-cause and melanoma-related mortality than the other patients.
CONCLUSIONS. Optic nerve invasion in uveal melanoma is found in 1 in 20 patients. Visible juxtapapillary melanoma or loss of light perception should make the clinician suspicious of melanoma with optic nerve invasion, and special awareness of postlaminar spread should be addressed when increased IOP is present independently of decreased visual acuity and tumor location.
The uveal melanoma material examined between 1942 and 2001 at the Eye Pathology Institute, University of Copenhagen, and the Institute of Pathology, Aarhus University Hospital, was reviewed to determine the frequency of optic nerve invasion and to identify clinical factors associated with optic nerve invasion. Furthermore, the metastatic pattern was investigated, and survival analyses were performed to determine the association between survival and optic nerve invasion.
| Materials and Methods |
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Ethics
The investigation followed the tenets of the Declaration of Helsinki and was approved by the local scientific ethical committee.
Clinical Characteristics
Reports from admitting hospitals were collected, and the following data on each patient were registered: sex, date of birth, date of histopathologic diagnosis, visual acuity, intraocular pressure (IOP), funduscopic examination, signs of extraocular growth at surgery, ocular surgery, radiotherapy, and orbital recurrence. Visual acuity and intraocular pressure were only included if these recordings were obtained within 2 weeks before enucleation. The tumor was classified as juxtapapillary if the clinician observed during funduscopic examination that the tumor was touching the optic disc. Signs of extraocular growth were graded as positive if the admitting physician had noted this in the surgical report or in the admission note. All pathology reports at the Eye Pathology Institute from 1942 to 2005 were also reviewed to detect orbital recurrences. Furthermore, the Danish Cancer Registry (DCR) was studied to detect orbital recurrences not treated with surgery.
Histopathology
All eyes were fixed in buffered formalin, embedded in paraffin, and stained with hematoxylin-eosin for routine histology diagnosis. All specimens were reexamined, and the degree of optic nerve invasion was graded as prelaminar or laminar if tumor cells were present in the optic nerve head or in the lamina cribrosa (Fig. 1 , left) and as postlaminar if tumor cells were present in the optic nerve or its sheaths cranial to the lamina cribrosa (Fig. 1 , right). Largest basal tumor diameter (LBD) was measured in millimeters, and the tumor was classified as small (
10 mm), medium (>1015 mm), or large (>15 mm).
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All death certificates were reviewed. If autopsy had been performed, the autopsy report was studied to validate the cause of death. If uveal melanoma metastases were found at autopsy, the patient was coded as having died of melanoma. If no autopsy had been performed and uveal melanoma was registered on the death certificate as the cause of death and the patient had no other malignancies according to the DCR, the patient was coded as having died of melanoma. If uveal melanoma or other malignancies were not noted on the death certificate and the patient was registered exclusively in the DCR with uveal melanoma, the patient was coded as having died of a nonmelanoma cause. If a malignancy other than uveal melanoma was registered as the cause of death on the death certificate and the patient was registered with this malignancy in the DCR, the patient was coded as having died of a nonmelanoma cause. Finally, if a malignancy other than uveal melanoma was registered as the cause of death but this malignancy was not registered in the DCR, the patient was coded as having died of melanoma (12 cases coded on the death certificate as skin melanoma, eight cases as gastrointestinal cancer, and one as unspecified malignancy). In eight cases, the cause of death could not be determined.
Statistical Analysis
Relationships between optic nerve invasion and clinical parameters were examined by contingency tables and were further analyzed by Pearson
2 test and Fisher exact test. Mean age and tumor size were analyzed by t test after verification of equal variances by Levene test. The equality of mean of intraocular pressure was tested by the Mann-Whitney U test because a nonnormal distribution was found. Correlations between ordinal parameters and optic nerve invasion were evaluated by Spearman rank correlation test.
Univariate and multivariate binary logistic regression analyses were performed in a forward stepwise manner to evaluate the predictive value of clinical factors for different degrees of optic nerve invasion. Factors with P < 0.20 in the univariate analysis were included in the multivariate analysis.
Survival data were obtained by the Kaplan-Meier method, and the Mantel-Cox log-rank test was used to test differences in survival between patient groups. Patients were excluded if no follow-up data were obtainable (n = 6). Patients with undetermined causes of death (n = 8) were excluded from the analysis of melanoma-related death. One patient with uveal melanoma diagnosed at autopsy was excluded from the survival analyses. Patients who died of causes unrelated to uveal melanoma were censored at the time of death in the analyses of melanoma-related death. P < 0.05 was regarded as significant.
| Results |
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Visual acuity was significantly reduced in patients with postlaminar invasion compared with the other patient groups (versus prelaminar or laminar, P < 0.001; versus control, P < 0.001; Table 1 ). Furthermore, patients with prelaminar or laminar invasion had significantly reduced visual acuity compared with controls (P = 0.027; Table 1 ).
Patients with postlaminar optic nerve invasion had significantly higher IOP (median, 48 mm Hg; 1470 mm Hg 10th90th percentiles) compared with other groups (prelaminar or laminar: median, 17 mm Hg; Hg 10th90th percentiles, 1250 mm; P < 0.001; control: median, 15 mm Hg; 10th90th percentiles, 1038 mm Hg; P < 0.001; Table 1 ). In addition, the frequency of increased IOP was higher in patients with prelaminar or laminar optic nerve invasion than in the controls (P = 0.003; Table 1 ).
In 38% (95% CI, 24%52%) of patients with postlaminar invasion, no view of the fundus was obtainable by direct funduscopic examination, primarily because of vitreous hemorrhage or total retinal detachment, compared with only 8% (95% CI, 2%14%; P < 0.001) among controls.
At direct funduscopic examination, the tumor was observed as juxtapapillary in 66% (95% CI, 48%83%) of the cases with postlaminar invasion and in 71% (95% CI, 60%83%) of the cases with prelaminar or laminar invasion (Table 1) . In 15% (95% CI, 7%24%) of the controls, the tumor was observed as juxtapapillary.
A significantly higher proportion of tumors with postlaminar invasion (19%) were thought by the surgeon to include extraocular extension compared with those with prelaminar or laminar invasion (5%; P = 0.004). Orbital recurrence was significantly more common among patients with postlaminar invasion (8%; 95% CI, 2%15%) than in controls (1%; 95% CI, 0%3%; P < 0.05).
Tumors with postlaminar optic nerve invasion (mean LBD, 16 mm; 95% CI, 1417 mm) were significantly larger than the other tumors (prelaminar or laminar: mean LBD, 13 mm; 95% CI, 1114 mm; P = 0.001; controls: mean LBD, 13 mm; 95% CI, 1214 mm; P < 0.001).
Before enucleation, three patients with prelaminar or laminar optic nerve invasion were treated with Ru-106 brachytherapy; one of those patients was treated twice. Two patients had been treated with transpupillary thermotherapy (TTT) and one (in 1962) with photocoagulation and external radiation. Radiation was used in an attempt to save the eye because the other one was no longer functional. Before enucleation, three patients with postlaminar optic nerve invasion were treated with Ru-106 brachytherapy and two were treated with TTT. In the control group, three patients were treated with Ru-106 brachytherapy and none were treated with TTT.
In addition, before enucleation, six (8%) patients with postlaminar optic nerve invasion, nine (11%) patients with prelaminar or laminar invasion, and eight (9%) patients in the control group had undergone various types of ocular surgery (e.g., iridectomy, sclerotomy).
Univariate binary logistic regression analysis showed that intraocular pressure greater than 24 mm Hg and juxtapapillary location were associated with prelaminar or laminar optic nerve invasion (Table 2) . The only clinical factor that was significantly associated with prelaminar or laminar optic nerve invasion of uveal melanoma on a multivariate level was juxtapapillary location (Table 2) .
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Metastatic disease was found in 53% of deceased patients with prelaminar or laminar optic nerve invasion and in 63% of patients with postlaminar optic nerve invasion. Metastatic disease developed in 43 (61%) patients in the control group (Table 3) . The liver was the most frequent site of metastasis in all three patient groups, followed by the lungs (Table 3) . Evidence of metastasis to the central nervous system (CNS), kidney, heart, or adrenal glands was only found in patients with optic nerve invasion. All five patients with postlaminar optic nerve invasion and metastases to the CNS had invasion of tumor cells into the subarachnoidal space. In two of these patients, the tumor was confined to the subarachnoidal space and the optic nerve sheaths. Significantly more autopsies were performed in patients with prelaminar or laminar invasion than in controls (P = 0.004; Table 3 ).
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One-hundred eighteen patients died of uveal melanoma, 74 patients died of other causes, and 35 were still alive at the end of follow-up. In eight patients the cause of death was undetermined. These eight patients were excluded from the analysis of melanoma-related death.
Two hundred twenty-seven patients (120 men, 107 women) were included in the analysis of melanoma-related death. Median follow-up time for all patients (n = 227) was 49 months (range, 1660 months), and for patients still alive (n = 35) it was 137 months (range, 28660 months). Median follow-up time was 53 months (range, 3660 months) for patients with prelaminar or laminar invasion, 23 months (range, 1495 months) for patients with postlaminar invasion, and 62 months (range, 1395 months) for patients in the control group.
Significant differences in mortality (all-cause and melanoma-related) were found between patients with postlaminar invasion and controls (all-cause, P = 0.001; melanoma-related, P = 0.017) and patients with prelaminar or laminar invasion (all-cause, P = 0.001; melanoma-related, P = 0.004; Figs. 4A 4B ). No significant differences in mortality were found between patients with prelaminar or laminar invasion and controls (all-cause, P = 0.93; melanoma-related, P = 0.49; Figs. 4A 4B ).
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| Discussion |
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NLP is an uncommon clinical feature in the presence of intraocular melanoma, yet in the present study it was seen in 24% (14/59) of patients with prelaminar or laminar and in 64% (35/55) of patients with postlaminar optic nerve invasion. Lack of light perception as a sign of postlaminar extension of a uveal melanoma is also supported by other case reports and series.7 15 16 17 18 The presence of increased IOP might cause nerve conduction loss, but the sole presence of neoplastic cells in the optic nerve might also disturb the functionality of the nerve fibers. Eight patients with optic nerve invasion and normal IOP in the present study had LP or NLP. Neoplastic cells alone thus appear to produce blindness because of nerve conduction loss.
Age older than 70 years was associated with postlaminar optic nerve invasion in patients with uveal melanoma. Age might be a surrogate for tumor size19 because melanomas with postlaminar invasion of the optic nerve were on average 3 mm larger in basal diameter than control melanomas and melanomas with prelaminar or laminar invasion. Why melanomas with postlaminar invasion of the optic nerve were larger than control melanomas may be explained by the possible presence of competing diseases affecting visual acuity. Hence, malignant melanomas in these patients may grow larger and more extensively into the optic nerve before they are diagnosed. In addition, the incidence of diseases affecting visual acuity is related to age, which can further exaggerate the age difference between the groups.
Increased IOP is seen in 3% of patients with uveal melanoma.20 In accordance with Shammas and Blodi7 and Spencer,15 increased IOP in the present study was associated with postlaminar optic nerve invasion. After multivariate analysis including tumor size, which is associated with IOP in uveal melanoma,3 increased IOP was significantly associated with postlaminar invasion of the optic nerve. Increased IOP and chronic vascular occlusive disease may induce optic nerve ischemia and edema, interrupting the integrity of the optic nerve tissue and thus facilitating the growth of malignant tumor cells.21 Spencer15 illustrates that blocked aqueous outflow leads to increased IOP and posterior flow in the degenerated vitreous. If the inner limiting membrane has been ruptured by a tumor, detached viable tumor cells can disperse posteriorly through the vitreous, adhere to the optic nerve head, and invade the optic nerve.15 However, increased IOP can also be a secondary phenomenon to uveal melanoma invading the optic nerve because a tumor in the posterior pole may compromise the posterior blood flow and induce rubeosis iridis and the formation of fibrovascular membranes in the trabecular area. Furthermore, the tumor itself may produce angiogenic factors that also facilitate the growth of fibrovascular membranes in the trabecular area.22 23 24 Even though a relation between optic nerve invasion and increased IOP was found, six patients with postlaminar invasion and 25 patients with prelaminar or laminar invasion had normal intraocular pressure, suggesting that factors in addition to increased IOP may be involved in optic nerve invasion. This hypothesis is supported by the transport of intravitreal silicone oil to the optic nerve in normotensive eyes.25
At direct funduscopic examination, no view of the fundus was seen in more than one third of cases with postlaminar invasion. This was attributed to total retinal detachment, tumor blocking the visual pathway, and vitreous hemorrhage. Weinhaus et al.13 use a histopathologic definition of juxtapapillary melanoma as melanoma in contact with the optic disc at any point. Consequently, in the present study, all melanomas with optic nerve invasion were juxtapapillary. Even though histopathologic examination might indicate a tumor is juxtapapillary, clinical examination might not reveal it to be in contact with the optic disc. In one third of the cases with visible fundus and uveal melanoma with postlaminar optic nerve invasion, the tumor was not identified as juxtapapillary, perhaps because transscleral illumination was not performed in all cases. This, in addition to the high frequency of a nonvisible fundus in patients with postlaminar invasion, affects the association of juxtapapillary location with postlaminar optic nerve invasion in multivariate analysis.
Orbital recurrence was statistically more frequent in patients with postlaminar optic nerve invasion than in control patients, in accordance with the findings of Affeldt et al.26 This is not surprising because the probability of total resection of the tumor is smaller if the tumor extends into the optic nerve, especially if no suspicion of optic nerve invasion was present before the enucleation. The higher incidence of orbital recurrence can partly explain why the mortality rate was higher among these patients than among control patients.
The metastatic pattern in uveal melanoma is different from that in cutaneous melanoma. The liver is affected in 80% to 100% of patients with uveal melanoma compared with 14% to 20% of those with cutaneous melanoma.3 5 6 27 28 29 Lung, bones, skin, and lymph nodes are other frequent sites of uveal melanoma metastasis.3 5 6 28 30 This is in accordance with findings in the control patients in the present study (Table 3) . Metastases to the heart, kidney, and CNS were found only in patients with optic nerve invasion, perhaps reflecting a different metastatic pattern in uveal melanomas with optic nerve invasion than in uveal melanomas without this feature. However, differences in the number of patients who underwent autopsy might have induced this difference in the present study (Table 3) . In addition, metastases to the heart were found almost exclusively at autopsy because clinical symptoms of these metastases are rare.31 32
Previous studies have demonstrated the frequency of CNS metastases in patients with uveal melanoma to be 4% to 15%.3 5 6 28 30 33 Interestingly, all patients in the present study who had metastases to the CNS also had optic nerve invasion. A possible route of dissemination in patients with postlaminar optic nerve invasion was by seeding through the cerebrospinal fluid because all these tumors had gained access to the subarachnoid space. In metastatic cutaneous melanoma, CNS metastases are detected clinically in 40% of patients and at autopsy in 90% of patients.34 35 The high CNS involvement may result from the common embryonic origin of melanocytes and neuronal subpopulations.36 This neurotropic propensity seems not to be present in uveal melanocytes, but a subpopulation may exist with this characteristic. Uveal melanoma may differ in response to growth-facilitating factors within the CNS and may interact in different ways with the CNS microenvironment. Differences in gene expression between tumors with and without brain metastases have been recognized in other tumors.37 38 The same possible difference in gene expression may also affect the propensity for optic nerve invasion of a uveal melanoma (neurotropic uveal melanoma).
The impact of optic nerve invasion on survival has been demonstrated in univariate analyses showing lower survival rates in patients with optic nerve invasion.3 10 26 39 However, when optic nerve invasion was included in multivariate analyses, the significance on survival disappeared.10 39
In the present study, we found a significant difference in survival between patients with postlaminar optic nerve invasion and the other patient groups. Patients with postlaminar invasion were older than the other patients. This affected all-cause mortality because of the higher incidence of competing causes of death. Melanoma-related mortality might have been greater in patients with postlaminar invasion because the tumors were larger and the frequency of orbital recurrence was greater.14 39 40 41 42 Studies have also demonstrated that age affects melanoma-related mortality.40 43
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| Acknowledgements |
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| Footnotes |
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Submitted for publication November 7, 2005; revised February 2 and March 22, 2006; accepted June 19, 2006.
Disclosure: J. Lindegaard, None; P. Isager, None; J.U. Prause, None; S. Heegaard, None
The publication costs of this article were defrayed in part by page charge payment. This article must therefore be marked "advertisement" in accordance with 18 U.S.C.
1734 solely to indicate this fact.
Corresponding author: Jens Lindegaard, Eye Pathology Institute, Frederik Vs Vej 11, 1 floor, DK-2100 Copenhagen, Denmark; jl{at}eyepath.ku.dk.
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