Prognosis and the concept of “low-risk” and high-risk” basal cell carcinomas
The histological subtype may correlate with prognosis, and thereby may be used to describe BCCs as low or high risk .
Management
The aim is to completely cure the tumour with the best cosmetic result. The early detection and appropriate (re-)treatment of either recurrent BCCs or new primary BCCs may help to increase the chances of permanent cure and to minimize morbidity. Patient education together with close collaboration with colleagues in primary care should allow the vast majority of adequately treated patients to be discharged back to the care of their general practitioners or dermatologists in private practice.
Surgical techniques
The most commonly used surgical techniques can be divided into main categories:
A.) Excision with predetermined margins
The aim of any excisional procedure is to eradicate the tumour entirely. Discussion of the surgical excision of BCC is divided into the following sections:
1 Primary (previously untreated) BCC. Surgical excision is a highly effective treatment for primary BCC. 18-19 (Strength of Evidence A, II-ii) The excised tissue can be examined histologically and the peripheral and deep surgical margins can be grossly assessed. The overall cosmetic results are usually good. The use of thorough curettage prior to excision of primary BCC may help to increase the cure rate by more accurately defining the true borders of the BCC. The size of the surgical margins should correlate with the likelihood that subclinical tumour extensions exist. Few data exist on the correct deep surgical margin, as this will depend upon the local anatomy. Studies using horizontal frozen sectioning Mohs micrographic surgery (MMS) to detect accurately BCC at any part of the surgical margin suggest that, for a small (< 20 mm) well defined BCC, 3 mm peripheral surgical margins will clear the tumour in 85% of cases (and a 4-5 mm margin will increase the peripheral clearance rate to approximately 95%, i.e. approximately 5% of small, well-defined BCCs show subclinical spread of > 4 mm. 2, 23) In contrast to small primary BCCs, morphoeic and large BCCs require wider surgical margins for complete histological resection. For primary morphoeic BCC, the rate of complete excision with increasing peripheral surgical margins is as follows: 3 mm margin: 66%, 5 mm margin: 82%, 13-15 mm margin: > 95%. 23 Positive margins are most often seen in morphoeic and facial tumours and are associated with a 26% recurrence rate over 5 years compared to 14% with free margins. 24 In the lid or periorbital area incompletely excised and morphoeic tumours were shown to have a 50% risk of recurrence.
2 Recurrent (previously treated) BCC. The results of all published series on the surgical excision of BCC show that cure rates for recurrent BCC are inferior to those for primary lesions. 26 Recurrent BCCs require wider peripheral surgical margins than primary lesions with or without standard (non-Mohs) frozen section control. Peripheral excision margins for recurrent BCC of 5-10 mm have been suggested. (Strength of Evidence A, II-ii)
3 Incompletely excised BCC (positive histological margins). This scenario should not occur following excision with histological control of margins. However if closure is completed before histological assessment there will be instances that the pathologist reports tumour present at the lateral and/or deep margin of excision. In some cases this may be apparent, not real, and due to tangential slicing of the specimen or tissue shrinkage. A study in which 43 incompletely excised BCCs were re-excised and the tissue examined using standard tissue sectioning techniques suggested that only 7% contained residual BCC. 28 However, when 78 incompletely excised BCCs were re-excised and examined using horizontal frozen sectioning (Mohs micrographic surgery) in order to detect BCC more accurately at any part of the surgical margin, 55% were found to contain residual BCC. 29 (Strength of Evidence A, II-iii) These findings were in accordance with another study demonstrating a tumour persistence in 28% of cases following incomplete excision of BCC. 30
Several studies have demonstrated that not all tumours will recur despite positive margins but the recurrence rate varies from 17-58%. The lowest rates were for lateral margin involvement only. The higher rates were for deep and lateral margin involvement, for tumours which were previously recurrent and those which had been treated by radiotherapy.
In a series of 187 incompletely excised BCCs, with 93% occurring on the head and neck, 119 were immediately retreated with radiotherapy, one was excised and 67 were not treated. After a median follow-up period of 2.7 years, statistical analysis suggested a 5-year probability of cure in the radiotherapy group of 91%, and in the untreated group of 61%.
So what advice should the patient be given?
Several studies have strongly recommended the immediate retreatment of incompletely excised BCC especially those where the surgical defect has been repaired using skin flaps or skin grafts. There may be occasions when a patient with a low risk primary tumour with possible lateral margin involvement opts for a period of observation. However generally it seems appropriate to re-excise with or without frozen section control or Mohs micrographic surgery.
B.) Stepwise excision with histology control of margins
Micrographic surgery might serve as a treatment of choice for large or difficult primary BCC lacking distinct clinical boundaries. The histological mapping of the tumour’s margins preserves tumour-free adjacent tissue, optimizes wound reconstruction and reduces the percentage of additional excisions in order to remove the tumour completely. 38 (Strength of Evidence A II-iii) This specialized minimal surgery was initially developed by Mohs and offers highly accurate yet conservative removal of BCC.
A review of all studies published since 1947 suggested an overall 5-year cure rate of 99% following Mohs micrographic surgery for primary BCC 41 and a review of all studies published since 1945 suggested an overall 5-year cure rate of 94.4% following Mohs micrographic surgery for recurrent BCC. 26 In addition to Mohs micrographic surgery, further fresh tissue micrographic techniques exist: both the margin strip method (“Tübinger Torte”) as well as the “Munich” method follow the same aim of complete tumour resection though they differ in some points, for example in the preparation or technique of tumour excision. The latter method was the treatment of choice for the excision of 3065 BCCs in 2795 patients. In 53.3% of all BCC, the first excision led to a complete tumour removal, another 36.9% were free of BCC after a second excision. Interestingly, clearance with one step excision ranged between 80% of adenoid-cystic, >50% of solid but only 43% of morphea-like BCC. The follow-up period over more than 5 years resulted in recurrences of BCC in 41 of 1604 patients (2.6%). 36% of these recurrent BCCs were re-recurrent tumours, 64% of these tumours were initially primary BCCs.
When compared with other outpatient-based treatments for BCC, these specialized methods undoubtedly offer high cure rates but are relatively expensive and time consuming.
The histological subtype may correlate with prognosis, and thereby may be used to describe BCCs as low or high risk .
Management
The aim is to completely cure the tumour with the best cosmetic result. The early detection and appropriate (re-)treatment of either recurrent BCCs or new primary BCCs may help to increase the chances of permanent cure and to minimize morbidity. Patient education together with close collaboration with colleagues in primary care should allow the vast majority of adequately treated patients to be discharged back to the care of their general practitioners or dermatologists in private practice.
Surgical techniques
The most commonly used surgical techniques can be divided into main categories:
A.) Excision with predetermined margins
The aim of any excisional procedure is to eradicate the tumour entirely. Discussion of the surgical excision of BCC is divided into the following sections:
1 Primary (previously untreated) BCC. Surgical excision is a highly effective treatment for primary BCC. 18-19 (Strength of Evidence A, II-ii) The excised tissue can be examined histologically and the peripheral and deep surgical margins can be grossly assessed. The overall cosmetic results are usually good. The use of thorough curettage prior to excision of primary BCC may help to increase the cure rate by more accurately defining the true borders of the BCC. The size of the surgical margins should correlate with the likelihood that subclinical tumour extensions exist. Few data exist on the correct deep surgical margin, as this will depend upon the local anatomy. Studies using horizontal frozen sectioning Mohs micrographic surgery (MMS) to detect accurately BCC at any part of the surgical margin suggest that, for a small (< 20 mm) well defined BCC, 3 mm peripheral surgical margins will clear the tumour in 85% of cases (and a 4-5 mm margin will increase the peripheral clearance rate to approximately 95%, i.e. approximately 5% of small, well-defined BCCs show subclinical spread of > 4 mm. 2, 23) In contrast to small primary BCCs, morphoeic and large BCCs require wider surgical margins for complete histological resection. For primary morphoeic BCC, the rate of complete excision with increasing peripheral surgical margins is as follows: 3 mm margin: 66%, 5 mm margin: 82%, 13-15 mm margin: > 95%. 23 Positive margins are most often seen in morphoeic and facial tumours and are associated with a 26% recurrence rate over 5 years compared to 14% with free margins. 24 In the lid or periorbital area incompletely excised and morphoeic tumours were shown to have a 50% risk of recurrence.
2 Recurrent (previously treated) BCC. The results of all published series on the surgical excision of BCC show that cure rates for recurrent BCC are inferior to those for primary lesions. 26 Recurrent BCCs require wider peripheral surgical margins than primary lesions with or without standard (non-Mohs) frozen section control. Peripheral excision margins for recurrent BCC of 5-10 mm have been suggested. (Strength of Evidence A, II-ii)
3 Incompletely excised BCC (positive histological margins). This scenario should not occur following excision with histological control of margins. However if closure is completed before histological assessment there will be instances that the pathologist reports tumour present at the lateral and/or deep margin of excision. In some cases this may be apparent, not real, and due to tangential slicing of the specimen or tissue shrinkage. A study in which 43 incompletely excised BCCs were re-excised and the tissue examined using standard tissue sectioning techniques suggested that only 7% contained residual BCC. 28 However, when 78 incompletely excised BCCs were re-excised and examined using horizontal frozen sectioning (Mohs micrographic surgery) in order to detect BCC more accurately at any part of the surgical margin, 55% were found to contain residual BCC. 29 (Strength of Evidence A, II-iii) These findings were in accordance with another study demonstrating a tumour persistence in 28% of cases following incomplete excision of BCC. 30
Several studies have demonstrated that not all tumours will recur despite positive margins but the recurrence rate varies from 17-58%. The lowest rates were for lateral margin involvement only. The higher rates were for deep and lateral margin involvement, for tumours which were previously recurrent and those which had been treated by radiotherapy.
In a series of 187 incompletely excised BCCs, with 93% occurring on the head and neck, 119 were immediately retreated with radiotherapy, one was excised and 67 were not treated. After a median follow-up period of 2.7 years, statistical analysis suggested a 5-year probability of cure in the radiotherapy group of 91%, and in the untreated group of 61%.
So what advice should the patient be given?
Several studies have strongly recommended the immediate retreatment of incompletely excised BCC especially those where the surgical defect has been repaired using skin flaps or skin grafts. There may be occasions when a patient with a low risk primary tumour with possible lateral margin involvement opts for a period of observation. However generally it seems appropriate to re-excise with or without frozen section control or Mohs micrographic surgery.
B.) Stepwise excision with histology control of margins
Micrographic surgery might serve as a treatment of choice for large or difficult primary BCC lacking distinct clinical boundaries. The histological mapping of the tumour’s margins preserves tumour-free adjacent tissue, optimizes wound reconstruction and reduces the percentage of additional excisions in order to remove the tumour completely. 38 (Strength of Evidence A II-iii) This specialized minimal surgery was initially developed by Mohs and offers highly accurate yet conservative removal of BCC.
A review of all studies published since 1947 suggested an overall 5-year cure rate of 99% following Mohs micrographic surgery for primary BCC 41 and a review of all studies published since 1945 suggested an overall 5-year cure rate of 94.4% following Mohs micrographic surgery for recurrent BCC. 26 In addition to Mohs micrographic surgery, further fresh tissue micrographic techniques exist: both the margin strip method (“Tübinger Torte”) as well as the “Munich” method follow the same aim of complete tumour resection though they differ in some points, for example in the preparation or technique of tumour excision. The latter method was the treatment of choice for the excision of 3065 BCCs in 2795 patients. In 53.3% of all BCC, the first excision led to a complete tumour removal, another 36.9% were free of BCC after a second excision. Interestingly, clearance with one step excision ranged between 80% of adenoid-cystic, >50% of solid but only 43% of morphea-like BCC. The follow-up period over more than 5 years resulted in recurrences of BCC in 41 of 1604 patients (2.6%). 36% of these recurrent BCCs were re-recurrent tumours, 64% of these tumours were initially primary BCCs.
When compared with other outpatient-based treatments for BCC, these specialized methods undoubtedly offer high cure rates but are relatively expensive and time consuming.
Posted in: Oncology and Cancer Articles
1 comments:
I really like to read.Hope to learn a lot and have a nice experience here! my best regards guys!
Laser Stafford VA
Post a Comment