2. The concept of the sentinel lymph node

The sentinel lymph node is the one which drains the lymph from the tumor first [15]. We assume that the tumor thrombus stops in the first lymph node that it reaches, and if there are no metastases in this lymph node, there will also be none in the other lymph nodes.

This concept is widely accepted in the surgical treatment of the malignant melanoma of the skin, as well as in the surgical treatment of breast cancer [16, 17]. In the treatment of the malignancies of the head and neck, there is a problem, which was highlighted by O'Brien [18], in the use of the concept of the sentinel lymph node due to the proximity of the tumor and the sentinel lymph node, rapid spread of the radiocolloid in the lymphatic pathways, a large number of the lymph nodes accumulating the radiocolloid, and often small, hard to reach lymph nodes.

Even though these difficulties referred to the skin melanomas, we encounter the same problems in the surgical treatment of squamous cell carcinoma of the upper airways and upper digestive tract. This is one of the main reasons why the use of the concept of the sentinel lymph node in the head and neck tumors is not widespread. The other important reason is that we do not have a fast and accurate method with which we could intraoperatively discover all of the metastases of the sentinel lymph nodes [19, 20]. A big problem arises if a pathologist discovers after the surgery the metastases in the lymph nodes that were not discovered with a frozen section procedure. In these cases, a reoperation is required, usually done 3–4 weeks after the initial surgery. Although we know that this can happen, it is still a very unpleasant experience for both the patient and the surgeon.

need to treat the contralateral side of the neck, what are the chances of successful treatment of

Clinical examination with palpation is absolutely not sufficient for discovering small and occult metastases [4]. Newer methods such as ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) allow for a discovery of more occult metastases, but their use also results in a large number of false positive metastases [5]. With the use of CT and MRI, there is also a limitation of discovering the metastases of lymph nodes smaller than 5 mm [3]. The best results are achieved with the ultrasound investigation of the neck combined with a cytologic punction [6]. Currently, no method is able to identify all of the occult metastases [7]. Therefore, we perform an elective dissection in the patients where more than 20% of occult metastases are expected [8–10]. Despite this, there remain a certain percentage of patients in whom the regional recurrences of the operated neck occur [11, 12]. Why is that? How can we overcome this? The most likely explanation is the unrecognized metastases in the dissected lymph nodes of the neck, overlooked by the classical histopathological examination. This oversight leads to inadequate treatment (no adjuvant radiotherapy) in these patients. An accurate neck status can be acquired by the use of the concept of the sentinel lymph node.

There is a large increase of patients with changed classification even with the use of only a classical histopathological examination. According to the literature, the classification increases in 49% and decreases in 21% [13]. With the use of classical histopathological examination, the pathologist examines the removed lymph nodes with one or two cuts along the longitudinal axis, which can lead to the oversight of the smaller metastases. With the use of the concept of sentinel lymph node, the lymph nodes are examined with serial cuts and immunochemical staining. This means that we can discover all of the metastases and can accurately determine the classification of the neck, which leads to the discovery of additional patients needing the adjuvant therapy. If elective dissection and checking for metastases of the lymph nodes are not performed, and we delay the adjuvant treatment until the possible appearance of metastases of

The sentinel lymph node is the one which drains the lymph from the tumor first [15]. We assume that the tumor thrombus stops in the first lymph node that it reaches, and if there are

This concept is widely accepted in the surgical treatment of the malignant melanoma of the skin, as well as in the surgical treatment of breast cancer [16, 17]. In the treatment of the malignancies of the head and neck, there is a problem, which was highlighted by O'Brien [18], in the use of the concept of the sentinel lymph node due to the proximity of the tumor and the sentinel lymph node, rapid spread of the radiocolloid in the lymphatic pathways, a large number of the lymph nodes accumulating the radiocolloid, and often small, hard to reach

no metastases in this lymph node, there will also be none in the other lymph nodes.

the regional lymph nodes, the prognosis is worse [14].

2. The concept of the sentinel lymph node

lymph nodes.

86 Cancer Survivorship

regional recurrences, and can we adjust the treatment to the etiology of the tumor [3].

The examination of the sentinel lymph node with serial cuts and immunohistochemical staining allows for the discovery of even the smallest metastases [21]. It is important that if no metastases are found in the sentinel lymph node, there were also none in the other lymph nodes [22].
